Patent Publication Number: US-9899174-B2

Title: Bipolar magnetic latching relay

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a 35 U.S.C. § 371 National Phase conversion of PCT/CN2013/088158, filed Sep. 29, 2013, which claims benefit of Chinese application no. 201310572264.X, filed Nov. 15, 2013, the disclosures of which are incorporated herein by reference in their entirety. The PCT International Application was published in the Chinese language. 
     TECHNICAL FIELD 
     The present invention relates to a magnetic latching relay, in particular to a bipolar magnetic latching relay suitable for an electric card charge meter design. 
     BACKGROUND ART 
     The magnetic latching relay is widely applied to various fields, such as electric appliances, electricity, offices, communication and aerospace in the current society. An electromagnetic system of the magnetic latching relay uses a permanent magnet instead of traditional coil magnetization, an input form of the permanent magnet is a pulse electric signal having certain width, and a conversion control form of an on-off state of the permanent magnet is to input a trigger electric signal to the coil; and during operation, only a pulse signal needs to be added to the coil to realize attraction of the coil, without long-term electrified magnetization, the retention of a normally-opened or normally-closed state of the magnetic latching relay depends on magnetism storage of permanent magnetic steel, and therefore compared with the traditional electromagnetic relay, the magnetic latching relay has the characteristic of low power consumption and reliable to attract, thus satisfying the requirements of energy saving and environmental friendliness in the current society. The magnetic latching relay used for an electric card charge meter at present is subject to electrified magnetization by the coil to generate magnetism the same or opposite to that of the permanent magnet to rotate armature, so as to impel a pushing card to move, and at this moment, main contacts of the relay are closed or separated, and a circuit is switched on or switched off. In general, the relay only has a pair of movable or static contacts with large resistance and high temperature rise, over travel is generated by self deformation of a movable flat spring, and since the movable flat spring has a short lever force arm, in order to ensure the movement property, the contact retention force cannot be too large. 
     EP 2009665 B1 Patent discloses a bipolar relay which adopts a solution in which an anchoring rocker arm with a permanent magnet drives an adjusting part to slide in a deflecting direction of contact springs two monopole relays, wherein the anchoring rocker arm is located in the middle of the adjusting part, and both end parts of the adjusting part are movably coupled to contact springs of each monopole relay a contact device of each monopole relay respectively; and the bipolar relay has the defects residing in that the adjusting parts of two poles are of an integral structure and are unavailable for accurate orientation, which causes that contact parameters are hard to debug, thus giving rise to poor synchronism of the on-off actions of each relay contacts of two poles, obvious temperature rise of relay contacts, ideal closing/disconnecting stability and reliability of contacts and difficulty to installation and debugging. The main reason for these defects resides in that the problems of principle conflict of mechanism and unreasonable design are present, wherein the principle conflict of mechanisms is mainly reflected in two coupling mechanisms by which both end parts of the adjusting part are movably coupled to the two contact springs respectively, to be specific, 1, the synchronisms of the on-off actions of the relay contacts of two poles are not ideal owing to the presence of the movement property conflict, 2, the synchronisms consistence of contact property resistances of the contact relays of two poles are not ideal owing to the presence of the matching conflict, and 3, the assembly process of a product conflicts with debugging and correcting measures that are necessary to be adopted for realizing ideal properties owing to the presence of installing installation and debugging conflicts. Because the desynchrony of the on-off actions and the contact resistances of the two coupling mechanisms caused by manufacturing errors of relevant parts is inevitable, and when the on-off action property of one coupling mechanism changes, the on-off action property of the other coupling mechanism changes correspondingly, and therefore, it is unavailable to adopt a correcting measure of debugging the on-off action property of one coupling mechanism by reference to the on-off action property of the other coupling mechanism, to cause that the on-off actions of the relay contacts of two poles are hard unlikely to achieve the requirement of synchronism. In addition, when the contact pressure of contacts of one coupling mechanism changes, the contact pressure of contacts the other coupling mechanism changes correspondingly, and therefore it is unavailable to realize the purpose of synchronously debugging and correcting the contact pressures of the contacts of the two coupling mechanisms to ideal requirements. When the difference between the contact resistances of relay contacts of two poles are quite large: if the relay contacts of two poles are connected to a loading loop in series, the temperature rise will be concentrated toward the contact having larger contact resistance, such that the temperature rise of the contacts is quickened; but if the relay contacts of two poles control two loading loops respectively, the temperature rise of the two contacts are unbalanced, to affect the current-carrying capability of output loops. Further, because two coupling mechanism of the prior art are coupling fit with free ends of two contact springs and additional springs through one adjusting part, and meanwhile the adjusting part is also in connecting fit with the anchoring rocker arm, coupling cooperation among the anchoring rocker arm, the adjusting part, free ends of the two contact springs and two additional springs is necessary to reach the ideal degree in order to obtain ideal properties, however, under the restraint from the structure of one adjusting part and the principle of the coupling mechanisms, when coupling fit between the free end of one contact spring and/or one additional spring and the adjusting part is debugged, coupling fit between the free end of the contact spring of the other coupling mechanism and/or one additional spring and the adjusting part will change, thus causing very difficult assembly and debugging and affecting the promotion of the production efficiency and the product quality. 
     SUMMARY OF THE INVENTION 
     In order to overcome the defects of the prior art, an objective of the invention is to provide a bipolar magnetic latching relay which adopts two guide transmission parts that are respectively connected with two driving balls of a magnetic steel assembly and free ends of two groups of movable contacts, wherein two groups of movable contacts are pushed by two driving balls respectively to act, thus forming two output loops of which the on-off actions simultaneously control on/off of the two output loops, and the output loops have the capability of loading power current, thus not only reducing the temperature rise and ensuring the working reliability of the relay, but also ensuring that the whole relay is reasonable in design with compact structure and attractive appearance. 
     In order to realize said purpose, the invention adopts the following technical solutions. 
     The bipolar magnetic latching relay comprises a coil assembly  14  mounted inside a cavity formed by buckling a shell cover  8  and a base  3 , a magnetic steel assembly  5  that contains a permanent magnet  59  and armatures  52 ,  53 ,  54  and  55 , as well as a first contact device  1  and a second contact device  2  that are mounted at both sides of the base  3 , wherein the magnetic steel assembly  5  is pivotally connected with the base  3  through a revolving pair  50 , the magnetic steel assembly  5  swings between two positions under the driving of an electric signal of the coil assembly  4  and is retained in one swing position due to the permanent magnetic force of the magnetic steel assembly  5 , and said swing synchronously the deflection of the first contact device  1  and the second contact device  2 , such that a first movable contact  17  and a first static contact  16  on a free end  15  of a first movable flat spring  10  of the first contact device  1  are subjected to closed/disconnecting fit, and meanwhile a second movable contact  27  and a second static contact  26  on a free end  25  of a second movable flat spring  20  of the second contact device  2  are subjected to closed/disconnecting fit. The bipolar magnetic latching relay is characterized in that the magnetic steel assembly  5  is provided with a first driving head  56  and a second driving head  57  that rotate synchronously with the magnetic steel assembly  5 , and both the first driving head  56  and the second driving head  57  extend to the outside from the same direction C of the magnetic steel assembly  5 ; the bipolar magnetic latching relay further comprises a guide transmission part  6  and a second guide transmission part  7  that connect each of the contact devices  1 ,  2  and the magnetic steel assembly  5 , wherein a first guide mechanism that allows the first guide transmission part  6  to move along a swing direction of the free end  15  of the first movable flat spring  10  is provided between the first guide transmission part  6  and the base  3 , a driven end  61  of the first guide transmission part  6  is connected with the first driving head  56  of the magnetic steel assembly  5  through a first driving connection structure, a driving end  62  of the first guide transmission part  6  is coupled to the free end  15  of the first movable flat spring  10  of the first contact device  1  through a first elastic transmission structure, a second guide mechanism that allows a second guide transmission part  7  to move along a swing direction of the free end  25  of the second movable flat spring  20  is provided between the second guide transmission part  7  and the base  3 , the second driven end  71  of the second guide transmission part  7  is connected with the second driving end  57  of the magnetic steel assembly  5 , and a driving end  72  of the second guide transmission part  7  is coupled to the free end  25  of the second movable flat spring  20  of the second contact device  2  through a second elastic transmission structure, such that the first guide transmission part  6  and the second guide transmission part  7  are the same in movement direction and simultaneously act. 
     Furthermore, as a preferred structure, the first guide mechanism comprises a guide groove  30  provided on the base  3  and a first sliding block  612  provided on the first guide transmission part  6 , the first sliding block  612  is mounted in the sliding groove  30  and is in sliding fit with the guide groove  30 , and the guiding direction of the guide groove  30  is parallel to the swing direction of the free end  15  of the first movable flat spring  10 ; and the second guide mechanism comprises a guide groove  30  provided on the base  3  and a second sliding block  712  provided on the second guide transmission part  7 , the second sliding block  712  is mounted in the guide groove  30  and is in sliding fit with the guide groove  30 , and the guiding direction of the guide groove  30  is parallel to the swing direction of the free end  25  of the second movable flat spring  20 . 
     One kind of the preferred structure of the first elastic transmission structure and the second elastic transmission structure resides in that the first elastic transmission structure comprises a first guide sliding surface  621 , a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide end surface  14 , a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first guide sliding surface  621  is in sliding fit with the first guide end surface  14 , the first disconnecting driving surface  622  is butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is butt fit with the first over-travel leaf spring  13 ; and the second elastic transmission structure comprises a second guide sliding surface  721 , a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , and a second guide end surface  24 , a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second guide sliding surface  721  is in sliding fit with the second guide end surface  24 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . 
     As another preferred structure of the first elastic transmission structure and the second elastic transmission structure resides in that the first elastic transmission structure comprises a first guide sliding rib  624 , a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide lug  31  provided on the base  3 , as well as a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first guide sliding rib  624  is in sliding fit with the first guide lug  31 , the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 ; and the second elastic transmission structure comprises a second guide sliding rib  724 , a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , and a second guide lug  32  provided on the base  3 , as well as a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second guide sliding rib  724  is in sliding fit with the second guide lug  32 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . 
     Another preferred structure of the first elastic transmission structure and the second elastic transmission structure resides in that the first elastic transmission structure comprises a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , as well as a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 ; and the second elastic transmission structure comprises a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , as well as a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . 
     As a further preferred structure of the first elastic transmission structure and the second elastic transmission structure, the first elastic transmission structure comprises a first guide sliding surface  621 , a first disconnecting driving surface  622 , a first closing driving surface  623  and a first guide sliding rib  624  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide end surface  14 , a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , and further comprises a first guide lug  31  that is provided on the base  3 , wherein the first guide sliding surface  621  is in sliding fit with the first guide end surface  14 , the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 , and the first guide sliding rib  624  is in sliding fit with the first guide lug  31 ; and the second elastic transmission structure comprises a second guide sliding surface  721 , a second disconnecting driving surface  722 , a second closing driving surface  723  and a second guide sliding rib  724  that are provided on the driving end  72  of the second guide transmission part  7 , and a second guide end surface  24 , a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , and further comprises a second guide lug  32  that is provided on the base  3 , wherein the second guide sliding surface  721  is in sliding fit with the second guide end surface  24 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 , and the second guide sliding rib  724  is in sliding fit with the second guide lug  32 . 
     Furthermore, as an optimized preferred structure, the first driving connection structure comprises a first connecting hole  611  provided in the driven end  61  of the first guide transmission part  6  and a spherical first driving head  56  that is provided on the magnetic steel assembly  5 , and the first driving head  56  is mounted in the first connecting hole  611  and is in contact fit with the first connecting hole  611 ; and the second driving connection structure comprises a second connecting hole  711  provided in the second driven end  71  of the second guide transmission part  7  and a spherical second driving head  57  that is provided on the magnetic steel assembly  5 , and the second driving head  57  is mounted in the second connecting hole  711  and is in contact fit with the second connecting hole  711 . 
     In addition, as an optimized preferred structure of the revolving pair  50 , the revolving pair  50  comprises a pivot  58  provided on the magnetic steel assembly  5 , a first pivot hole formed in the base  3  and a positioning part  9  provided with a second pivot hole, and both ends of the pivot  58  are mounted in the first pivot hole and the second pivot hole respectively in a pivot fit manner, and the positioning part  9  is fixedly mounted in on the base  3 . The As another preferred structure of the revolving pair  50 , the revolving pair  50  comprises a pivot  58  provided on the magnetic steel assembly  5 , a first pivot hole formed in the base  3  and a second pivot hole formed in a shell cover  8 , both ends of the pivot  58  are mounted in the first pivot hole and the second pivot hole respectively in a pivot fit manner, and the shell cover  8  is fixedly connected with the base  3 . 
     Moreover, as a preferred structure, a non-free end of the first movable flat spring  10  of the first contact device  1  is in U-shaped connection with a first movable connecting plate  11  and a first static connecting plate  12  respectively, and the first over-travel leaf spring  13  is a pressure leaf spring that participates in providing a final pressure for contacts; and the non-free end of the second movable flat spring  20  of the second contact device  2  is in U-shaped connection with a second movable connecting plate  21  and a second static connecting plate  22  respectively, and the second over-travel leaf spring  23  is a pressure leaf spring that participates in providing a final pressure for contacts. 
     The existing relay adopts one adjusting part such that a link for transferring movement is formed between two coupling mechanisms, and by means of the link, the action of one of the coupling mechanisms not only depends on normal control by an anchoring rocker arm, but also depends on surplus control by the other coupling mechanism, and the surplus control is harmful and will affect the action precision of the coupling mechanism, thus getting rise to harmful movement transfer between the two coupling mechanisms and harmful free movement present in the adjusting part. In addition, a design of a movement pair that connects the adjusting part and the free end of the contact spring lacks a necessary constraint of limiting the up-down movement of the adjusting part in addition that the connection between the anchoring rocker arm and the adjusting part has a seesaw-type fulcrum effect, such that the adjusting part at least has three fflat springom degrees of independent movement, wherein the fflat springom degree of transverse movement is design-specific, and the two fflat springom degrees of up-down movement and rotation around a fulcrum of the anchoring rocker arm are harmful and thus will affect the action precision of the existing coupling mechanisms. In allusion to the unreasonable design of the prior art, the bipolar magnetic latching relay of the present invention further adopts a first guide mechanism and a second guide mechanism in addition to adopting the first guide transmission part and the second guide transmission part to drive the first movable flat spring and the second movable flat spring respectively, such that two movement links that do not affect to each other are formed between the two coupling mechanisms, and therefore the movement constraint conditions between the two movement parts, namely the first guide transmission part and the second guide transmission part are perfected, the movement precision of the first guide transmission part and the second guide transmission part is greatly promoted, and thus the synchronism of the on-off actions between the two contact devices as well as the closing/disconnecting stability and reliability of contacts are effectively promoted, the current-loading and disconnecting capabilities of the bipolar magnetic latching relay are effectively enhanced, and the temperature rise is reduced. Meanwhile, a structure of preventing the driving end of each of the first guide transmission part and the second guide transmission part from sliding up and down is provided on the respective driving end to further promote the movement precision of the first guide transmission part and the second guide transmission part, such that the movable coupling property between respective first guide transmission part and second guide transmission part and respective first movable flat spring and second movable flat spring is better. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above features and technical advantages of the present invention are clearer and easily understood from the following description of the embodiments in conjunction with the accompanying drawings. 
         FIG. 1  is a planar schematic drawing representing the integral structure of the bipolar magnetic latching relay of the present invention. 
         FIG. 2  is a planar schematic drawing representing the bottom-view appearance of  FIG. 1 . 
         FIG. 3  is a planar schematic drawing representing the internal structure of the bipolar magnetic latching relay of the present invention of  FIG. 1 , wherein  FIG. 3  illustrates the integral structure of the components, such as the coil assembly  4 , the magnetic steel assembly  5 , the first guide transmission part  6  and the second guide transmission part  7 . 
         FIG. 4  is a stereoscopic schematic drawing representing the local structure of the first guide transmission part  6  and the second guide transmission part  7  of  FIG. 1 . 
         FIG. 5  is a stereoscopic schematic drawing representing the local structure of the second guide mechanism of the second guide transmission part  7  of  FIG. 1 . 
         FIG. 6  is a schematic drawing representing the stereoscopic structure of the first guide transmission part  6 . 
         FIG. 7  is a schematic drawing presenting the stereoscopic structure of the second guide transmission part  7 . 
         FIG. 8  is an enlarged drawing of the portion A of  FIG. 3 , which specifically illustrates the first elastic transmission structure between the first guide transmission part  6  and the first movable flat spring  10  of the first contact device  1 , wherein the first movable flat spring  10  of  FIG. 8  is at a closed state. 
         FIG. 9  is an enlarged drawing of the portion B of  FIG. 3 , which specifically illustrates the second elastic transmission structure between the first second guide transmission part  7  and the first second movable flat spring  20  of the first second contact device  2 , wherein the second movable flat spring  20  as shown in of  FIG. 9  is at a closed state. 
         FIG. 10  is a schematic drawing representing the stereoscopic structure of the magnetic steel assembly  5 . 
         FIG. 11  is a schematic drawing representing the stereoscopic structure of the coil assembly  4 . 
         FIG. 12  is a schematic drawing illustrating the planar structure of the movable flat spring  20  of the second contact device. 
     
    
    
     DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
     The specific embodiments of the bipolar magnetic latching relay of the present invention are further illustrated as below in conjunction with the embodiments presented by  FIGS. 1-12 . The bipolar magnetic latching relay of the present invention is limited to the description of the following embodiments. 
       FIG. 1  is the planar schematic drawing illustrating the integral structure of the bipolar magnetic latching relay of the present invention. As shown in  FIG. 1 , the bipolar magnetic latching relay of the present invention comprises a first contact device  1 , a second contact device  2 , a base  3 , a coil assembly  4 , a magnetic steel assembly  5 , a first guide transmission part  6 , a second guide transmission part  7  and a shell cover  8 . The base  3  and the shell cover  8  are buckled by a buckle  33  and are fixedly connected to form a cavity  300  in which the first contact device  1 , the second contact device  2 , the base  3 , the coil assembly  4 , the magnetic steel assembly  5 , the first guide transmission part  6  and the second guide transmission part  7  are mounted. An electromagnetic system of the relay, which consists of the coil assembly  4  with magnetic yokes and the magnetic steel assembly  5  that contains a permanent magnet  59  and armatures  52 ,  53 ,  54  and  55  is arranged in the middle of the base  3 , contact systems consisting of movable contacts and static contacts of the first contact device  1  and the second contact device  2  are mounted on the base  3  and distributed at both sides of the electromagnetic system, the free ends of the movable flat springs  10 ,  20  are connected with the movable contacts  17 ,  27  and over-travel leaf springs  13 ,  23  together, and the magnetic steel assembly  5  is pivotally connected with the base  3  through a revolving pair  50 . The magnetic steel assembly  5  swings between two positions under the driving of an electric signal of the coil assembly  4  and is retained in one swing position due to the permanent magnetic force of the magnetic steel assembly  5 , and the swing synchronously drives the first contact device  1  and the second contact device  2  to deflect, the magnetic steel assembly  5  rotates to drive the first guide transmission part  6  and the second guide transmission part  7  that are separately formed on one straight line, via driving balls that are located at the top end of the magnetic steel assembly  5  in the same direction, the latter synchronously pushes drives the movable contacts at both sides to act, thus realizing on/off of a circuit, that is to say, a first movable contact  17  and a first static contact  16  on the free end  15  of the first movable flat spring  10  of the first contact device  1  are subjected to closing/disconnecting fit, and meanwhile a second movable contact  27  and a second static contact  26  of the free end  25  of the second movable flat spring  20  of the second contact device  2  are subjected to closing/disconnecting fit. 
     As shown in  FIG. 10 , the magnetic steel assembly  5  is provided with a first driving head  56  and a second driving head  57  that synchronously rotate therewith, and both the first driving head  56  and the second driving head  57  extend to the outside from the same direction C of the magnetic steel assembly  5 ; and the first guide transmission part  6  and the second guide transmission part  7  are used for establishing a transmission connection between each of the contact devices  1 ,  2  and the magnetic steel assembly  5 , to be specific, a first guide mechanism that allows the first guide transmission part  6  to move along a swing direction of the free end  15  of the first movable flat spring  10  is provided between the first guide transmission part  6  and the base  3 , a driven end  61  of the first guide transmission part  6  is connected with the first driving head  56  of the magnetic steel assembly  5  through a first driving connection structure, a driving end  62  of the first guide transmission part  6  is coupled to the free end  15  of the first movable flat spring  10  of the first contact device  1  through a first elastic transmission structure, a second guide mechanism that allows the second guide transmission part  7  to move along a swing direction of the free end  25  of the second movable flat spring  20  is provided between the second guide transmission part  7  and the base  3 , a second driven end  71  of the second guide transmission part  7  is connected to the second driving end  57  of the magnetic steel assembly  5  through a second driving connection structure, and a driving end  72  of the second guide transmission part  7  is coupled to the free end  25  of the second movable flat spring  20  of the second contact device  2  through a second elastic transmission structure, with the purpose of allowing the first guide transmission part  6  and the second guide transmission part  7  to be the same in movement direction and simultaneously act. 
     Referring to  FIGS. 1, 2, 8 and 9 , the first contact device  1  is an output loop of a first pole and comprises a first movable connecting plate  11 , a first static connecting plate  12 , a first movable flat spring  10 , a first over-travel leaf spring  13 , a first static contact  16  and a first movable contact  17 , wherein one end of the first movable connecting plate  11  extends out of the cavity  300  for a purpose of wiring, and the other end of the first connecting plate  11  is located in the cavity  300  and fixedly mounted on the base  3 ; one end of the first movable flat spring  10  is a first fixed end  18  which is fixedly connected with the other end of the first movable connecting plate  11 ; the other end of the first movable flat spring  10  is a free end  15  which can swing with the first fixed end  18  as a fulcrum; one end of the first over-travel leaf spring  13  is fixedly connected with the free end  15  of the first movable flat spring  10  to form a cantilever structure; the first movable contact  17  is fixed on the free end  15  of the first movable flat spring  10  and swings with the free end  15  together with the first over-travel leaf spring  14 ; similarly, one end of the first static connecting plate  12  extends out of the cavity  300  for a purpose of wiring, the other end of the first static connecting plate  12  is located in the cavity  300  and is fixedly mounted on the base  3 , and the first static contact  16  is fixed on the first static connecting plate  12 . When the first guide transmission part  6  pushes the first over-travel leaf spring  13  towards a closing direction of contacts, the first over-travel leaf spring  13  drives the free end  15  and the first movable contact  17  on the free end  15  to swing towards the direction of the first static contact  16  till the first movable contact  17  and the first static contact  16  contact to be closed, such that the first movable connecting plate  11  and the first static connecting plate  12  are electrically switched on, and under a closed state as shown in  FIGS. 1, 3 and 8 , the first over-travel leaf spring  13  provides an elastic pressure for the first movable contact  17  and the first static contact  16 . When the first guide transmission part  6  pushes the free end  15  towards a disconnecting direction, the free end  15  drives the first over-travel leaf spring  13  on the free end to be separated from the first movable contact  17  and the first static contact  16 , such that the first movable connecting plate  11  and the first static connecting plate  12  are electrically separated. By means of the above-mentioned structure, the closing/disconnecting fit between the first movable contact  17  and the first static contact  16  on the free end  15  of the first movable flat spring  10  of the first contact device  1  is realized. The second contact device  2  is an output loop of a second pole and comprises a second movable connecting plate  21 , a second static connecting plate  22 , a second movable flat spring  20 , a second over-travel leaf spring  23 , a second static contact  26  and a second movable contact  27 , wherein one end of the second movable connecting plate  22  extends out of the cavity  300  for a purpose of wiring, and the other end of the second static connecting plate  22  is located in the cavity  300  and fixedly mounted on the base  3 ; one end of the second movable flat spring  20  is a second fixed end  28  which is fixedly connected with the other end of the second movable connecting plate  22 ; the other end of the second movable flat spring  20  is a free end  25  which can swing with the second fixed end  28  as a fulcrum; one end of the second over-travel leaf spring  23  is fixedly connected with the free end  25  of the second movable flat spring  20  to form a cantilever structure; the second movable contact  27  is fixed on the free end  25  of the second movable flat spring  20  and swings with the free end  25  together with the second over-travel leaf spring  23 ; similarly, one end of the second static connecting plate  21  extends out of the cavity  300  for a purpose of wiring, the other end of the second static connecting plate  21  is located in the cavity  300  and is fixedly mounted on the base  3 , and the second static contact  26  is fixed on the second static connecting plate  21 . When the second guide transmission part  7  pushes the second over-travel leaf spring  23  towards a closing direction of contacts, the second over-travel leaf spring  23  drives the free end  25  and the second movable contact  27  on the free end  25  to swing towards the direction of the second static contact  26  till the second movable contact  27  and the second static contact  26  contact to be closed, such that the second movable connecting plate  21  and the second static connecting plate  22  are electrically switched on, and under a closed state as shown in  FIGS. 1, 3 and 9 , the second over-travel leaf spring  23  provides an elastic pressure for the second movable contact  27  and the second static contact  26 . When the second guide transmission part  7  pushes the free end  25  towards a disconnecting direction, the free end  25  drives the second over-travel leaf spring  23  on the free end to be separated from the second movable contact  27  and the second static contact  26 , such that the second movable connecting plate  21  and the second static connecting plate  22  are electrically separated. By means of the above-mentioned structure, the closing/disconnecting fit between the second movable contact  27  and the second static contact  26  on the free end  25  of the second movable flat spring  20  of the second contact device  2  is realized. The first contact device  1  and the second contact device  2  are the same in the closing/disconnecting direction, namely, in the connecting process, the free end  15  of the first over-travel leaf spring  13  of the first contact device  1  has the same swing direction with the free end  25  of the second over-travel leaf spring  23  of the second contact device  2 . 
     By referring to  FIGS. 1, 3 and 10 , the magnetic steel assembly  5  comprises a shell  51 , a permanent magnet  59  mounted in the shell  51 , a first N terminal  54 , a first S terminal  55 , a second N terminal  52  and a second S terminal  53  that extend outwards from the interior of the shell  51 , as well as a first driving head  56  and a second driving head  57  that are used for driving the first guide transmission part  6  and the second guide transmission part  7  respectively. In the embodiment as shown in  FIG. 10 , the first S terminal  55  and the second S terminal  53  are located on the upper side (namely the S pole of the permanent magnet  59  is on the upper side), the first N terminal  54  and the second N terminal  52  are on the lower side (namely the N pole of the permanent magnet  59  is on the lower side), and the solution equivalent thereto resides in that the first S terminal  55  and the second S terminal  53  are on the lower side (namely the S pole of the permanent magnet  59  is on the lower side), and the first N terminal  54  and the second N terminal  52  are on the upper side (namely the N pole of the permanent magnet  59  is on the upper side). The first driving head  56  and the second driving head  57  extend to the outside from the same direction C of the magnetic steel assembly  5  and are integrally formed with the shell  51 , thus being capable of synchronously rotating with the magnetic steel assembly  5 . The first N terminal  54  and the second N terminal  52  are connected with the N pole of the permanent magnet  59  through a magnetic circuit, the first S terminal  55  and the second S terminal  53  are connected with the S pole of the permanent magnet  59  through a magnetic circuit, and such connection may be realized by well-known methods, for example, by guiding both ends of one armature out from the S pole of the permanent magnet  59  to form the first N terminal  54  and the second N terminal  52  and guiding another armature out from the S pole of the permanent magnet  59  to form the second S terminal  53  and the first S terminal  55 , and therefore the first N terminal  54  and the second N terminal  52  are N poles of the permanent magnet  59  respectively, and the first S terminal  55  and the second S terminal  53  are S poles of the permanent magnet  59  respectively. When the first magnetic yoke  41  and the second magnetic yoke  42  of the coil assembly  4  are free of exciting electromagnetism, the permanent magnetic force of the permanent magnet  59  still enables the magnetic steel assembly  5  to be kept at a current state (namely the state at the moment when an electric signal is removed from the coil assembly  4 ). The pivotal connection between the magnetic steel assembly  5  and the base  3  through the revolving pair  50  refers to that only one fflat springom degree of rotation around a rotation center of the magnetic steel assembly  5  is available after being the magnetic steel assembly  5  is mounted on the base  3 , multiple solutions for implementing the revolving pair  50  may be available, wherein one optimized preferred solution resides in that: the revolving pair  50  comprises a pivot  58  provided on the magnetic steel assembly  5 , a first pivot hole (not shown in Drawings) formed in the base  3  and a positioning part  9  provided with a second pivot hole (not shown in Drawings), wherein both ends of the pivot  58  are mounted in the first pivot hole and the second pivot hole in a pivot fit manner respectively, and the positioning part  9  is fixedly mounted on the base  3 . This solution is a preferred alternate alternative solution which has higher rotation precision and is easy to assemble and debug at the same time. Another solution resides in that: the revolving pair  50  comprises a pivot  58  provided on the magnetic steel assembly  5 , a first pivot hole (not shown in Drawings) formed in the base  3  and a second pivot hole (not shown in Drawings) formed in the shell cover  8 , wherein both ends of the pivot  58  are mounted in the first pivot hole and the second pivot hole in a pivot fit manner respectively, and the shell cover  8  is fixedly connected with the base  3 . This solution has the advantage that the positioning part  9  can be omitted, but has lower rotation precision while the difficulty in fixed connection between the shell cover  8  and the base  3  is increased. 
     Referring to  FIGS. 1, 3, 10 and 11 , the coil assembly  4  comprises a first magnetic yoke  41 , a second magnetic yoke  42 , a coil rack  43  and a coil  44 , wherein the coil  44  is sheathed outside the coil rack  43 , and the first magnetic yoke  41  and the second magnetic yoke  42  are respectively inserted into the coil rack  43  to form a magnetic circuit connection in the coil rack  43 . When a voltage/current (a pulse electric signal having certain width, for example) is loaded to the coil  44  through well-known methods, a magnetic field is generated on the first magnetic yoke  41  and the second magnetic yoke  42 , and the polarity of the first magnetic yoke  41  is opposite to that of the second magnetic yoke  42 ; when the polarity of the loaded pulse electric signal changes, the polarity of the first magnetic yoke  41  and the polarity of the second magnetic yoke  42  are converted correspondingly. The first magnetic yoke  41  of the coil assembly  4  is in attraction/repulsion fit with the first N terminal  54  and the first S terminal  55  of the magnetic steel assembly  5 , and the second magnetic yoke  42  of the coil assembly  4  is in attraction/repulsion fit with the second N terminal  52  and the second S terminal  53  of the magnetic steel assembly  5 , and the second magnetic yoke  42  of the coil assembly  4  is in pull-in/repulsion fit with the second N terminal  52  and the second S terminal  53  of the magnetic steel assembly  5 , namely when the loaded pulse electric signal enables the first magnetic yoke  41  to be an N pole and the second magnetic yoke  42  to be an S pole, the first S terminal  55  and the first magnetic yoke  41  are attracted to each other, the first N terminal  54  is repelled from the first magnetic yoke  41 , the second N terminal  52  and the second magnetic yoke  42  are attracted to each other and the second S terminal  53  is repelled from the second magnetic yoke  42 , and therefore the magnetic steel assembly  5  is driven to deflects leftwards till reaching a state as shown in  FIG. 3 . When the loaded pulse electric signal enables the first magnetic yoke  41  to be an S pole and the second magnetic yoke  42  to be an N pole, the first S terminal  55  is repelled from the first magnetic yoke  41 , the first N terminal  54  and the first magnetic yoke  41  are attracted to each other, the second N terminal  52  is repelled from the second magnetic yoke  42  and the second S terminal  53  and the second magnetic yoke  42  are attracted to each other, and therefore the magnetic steel assembly  5  is driven to deflect rightwards (namely deflects in a clockwise direction as shown in  FIG. 3 ) and is stabilized at an attraction state of deflecting rightwards (not shown in drawings). In the attraction state, even the electric signal loaded to the coil assembly  4  is removed, the magnetic force of the permanent magnet  59  in the magnetic steel assembly  5  still can enable the magnetic steel assembly  5  to be maintained at the current attraction state. It can thus be seen that the pulse electric signal is just to drive the magnetic steel assembly  5  to be converted into a deflection state, and the state of the magnetic steel assembly  5  is maintained in need of the magnetic force of the permanent magnet  59 . 
     Referring to  FIGS. 1, 3, 4, 6 and 7 , a first guide mechanism by which the first guide transmission part  6  moves along a swing direction of the free end  15  of the first movable flat spring  10  is arranged between the first guide transmission part  6  and the base  3 . The first guide mechanism may have a plurality of structure solutions, wherein one preferred solution resides in that: the first guide mechanism comprises a guide groove  30  provided on the base  3  and a first sliding block  612  provided on the first guide transmission part  6 , the guiding direction of the guide groove  30  is parallel to the swing direction of the free end  15  of the first movable flat spring  10 , and the first sliding block  612  is mounted in the guide groove  30  and is in sliding fit with the guide groove  30 . The guiding direction of the guide groove  30  refers to a direction that allows the first sliding block  612  to slide in the guide groove  30 , namely the length direction of the guide groove  30 . The guide groove  30  can limit the movement of the first sliding block  612  in a width direction and a depth direction of the guide groove  30 , both the width direction and the depth direction of the guide groove  30  are perpendicular to the guiding direction thereof, a rectangular sliding block can be adopted as the first sliding block  612 , and therefore the first guiding mechanism limits that the first guide transmission part  6  only has one fflat springom degree of linear movement, the direction of linear movement is consistent with the swing direction of the free end  15  of the first movable flat spring  10 , and thereby such structure greatly improves the movement precision of the first guide transmission part  6  and effectively overcomes a variety of defects caused by unreasonable design of a movement pair. The first guide transmission part  6  is a rodlike member one end of which is a driven end  61  and the other end is a driving end  62 . The driven end  61  is connected with the first driving head  56  of the magnetic steel assembly  5  through a first driving connection structure, the deflection action of the magnetic steel assembly  5  is transferred to the first guide transmission part  6  through the first driving connection structure, and by means of the transmission chain, the deflecting swing of the magnetic steel assembly  5  is converted to linear movement of the first guide transmission part  6 . There may be a plurality of specific implementations for the first driving connection structure, wherein one preferred implementation resides in that: the first driving connection structure comprises a first connecting hole  611  formed in the driven end  61  of the first guide transmission part  6  and a spherical first driving head  56  provided on the magnetic steel assembly  5 , and the first driving head  56  is mounted in the first connecting hole  611  and is in contact fit with the first connecting hole  611 . Such driving connection structure not only has high transmission precision, but also has a deflecting swing-linear movement conversion function. 
     In the same way, a second guide mechanism by which the second guide transmission part  7  moves along the swing direction of the free end  25  of the second movable flat spring  20  is provided between the second guide transmission part  7  and the base  3 . A plurality of structure solutions may be available for the second guide mechanism, wherein one optimized preferred solution resides in that: the second guide mechanism comprises a guide groove  30  provided on the base  3  and a second sliding block  712  provided on the second guide transmission part  7 , the guiding direction of the guide groove  30  is parallel to the swing direction of the free end  25  of the second movable flat spring  20 , and the second sliding block  712  is mounted in the guide groove  30  and is in sliding fit with the guide groove  30 . A rectangular sliding block can be adopted as the second sliding block  712 , and therefore the second guiding mechanism limits that the second guide transmission part  7  only has one fflat springom degree of linear movement, and the direction of linear movement is consistent with the swing direction of the free end  25  of the second movable flat spring  20 . The second guide transmission part  7  is a rodlike member one end of which is a second driven end  71  and the other end is a driving end  72 . The second driven end  71  is connected with the second driving head  57  of the magnetic steel assembly  5  through a second driving connection structure, the deflection action of the magnetic steel assembly  5  is transferred to the second guide transmission part  7  through the second driving connection structure, and by means of the transmission chain, the deflecting swing of the magnetic steel assembly  5  is converted to linear movement of the second guide transmission part  7 . A plurality of specific implementation solutions may be available for the second driving connection structure, wherein one preferred solution resides in that: the second driving connection structure comprises a second connecting hole  711  formed in the driven end  71  of the second guide transmission part  7  and a spherical second driving head  57  provided on the magnetic steel assembly  5 , and the second driving head  57  is mounted in the second connecting hole  711  and is in contact fit with the second connecting hole  711 . The guide groove  30  is additionally provided with the base  3 , and the two guiding transmission parts are provided with guide ribs and contact guide devices, such that the first guide transmission part  6  and the second guide transmission part  7  are the same in movement direction and synchronously act, and the two guide transmission parts can realize the movement in the horizontal direction furthest, effectively adjust the contact parameters, avoid desynchrony of two phases caused by inclination of the transmission parts and increase the contact pressure. 
     Referring to  1 ,  3 ,  4 ,  6 ,  8  and  10 , the driving end  62  of the first guide transmission part  6  is movably coupled to the free end  15  of the first movable flat spring  10  through a first elastic transmission structure, and by means of the movement being together upon this coupling, the first guide transmission part  6  transfers actions to the free end  15  of the first movable flat spring  10 , and the linear movement of the first guide transmission part  6  is converted into deflecting swing of the free end  15  to drive closing/disconnecting of the first movable contact  17  and the first static contact  16 . A plurality of specific solutions may be available for the first elastic transmission structure, and may be divided into four implementation forms according to the difference of properties of preventing the driving end  62  of the first guide transmission  6  from swinging up and down. The property that the driving end  62  swings up and down is associated to a process during which the first guide transmission part  6  controls the free end  15  of the first movable flat spring  10  to do a closing/disconnecting operation, and with respect to the amplitude of up-down free slippage of the free end  15 , the larger the slippage is and the larger the harm is. Although the first guide mechanism has a favorable function of preventing the slippage, the effect of achieving the result with half effort can be achieved still since the first elastic transmission structure contains a structure of preventing the slippage, in order to further strength the technical effect pursued for the purpose of the present invention. Four preferred solutions for the first elastic transmission structure having different anti-slippage properties are proposed as below. 
     The first solution resides in that: the first elastic transmission structure comprises a first guide sliding surface  621 , a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide end surface  14 , a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first guide sliding surface  621  is in sliding fit with the first guide end surface  14 , the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 . It is obvious that the sliding fit between the first guide sliding surface  621  and the first guide end surface  14  can further prevent downward slippage of the driving end  62 . In order to further prevent upward slippage of the driving end  62 , the following matched solution may be selected: under the butt joint state during a butt fit process of the first closing driving surface  623  and the first over-travel leaf spring  13  of the first elastic transmission structure, the elastic force F that the first over-travel leaf spring  13  acts to the first closing driving surface  623  includes a component force Fy that drives the first closing driving surface  623  to move downwards. 
     The second solution resides in that: the first elastic transmission structure comprises a first guide sliding surface  621 , a first disconnecting driving surface  622 , a first closing driving surface  623  and a first guide sliding rib  624  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide end surface  14 , a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , and further comprises a first guide lug  31  that is provided on the base  3 , wherein the first guide sliding surface  621  is in sliding fit with the first guide end surface  14 , the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 , and the first guide sliding rib  624  is in sliding fit with the first guide lug  31 . It is obvious that the sliding fit between the first guide sliding surface  621  and the first guide end surface  14  can further prevent downward slippage of the driving end  62 , and the sliding fit between the first guide sliding rib  624  and the first guide lug  31  can further prevent upward slippage of the driving end  62 . 
     The third solution resides in that: the first elastic transmission structure comprises a first guide sliding rib  624 , a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , and a first guide lug  31  provided on the base  3  as well as a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first guide sliding rib  624  is sliding fit with the first guide lug  31 , the first disconnecting driving surface  622  is butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is butt fit with the first over-travel leaf spring  13 . It is obvious that the sliding fit between the first guide sliding rib  624  and the first guide lug  31  can further prevent upward slippage of the driving end  62 . 
     The fourth solution resides in that: the first elastic transmission structure comprises a first disconnecting driving surface  622  and a first closing driving surface  623  that are provided on the driving end  62  of the first guide transmission part  6 , as well as a first disconnecting side surface  150  and a first over-travel leaf spring  13  that are provided on the free end  15  of the first movable flat spring  10 , wherein the first disconnecting driving surface  622  is in butt fit with the first disconnecting side surface  150 , and the first closing driving surface  623  is in butt fit with the first over-travel leaf spring  13 . It is obvious that such first elastic transmission structure does not comprise a structure of preventing the driving end  62  from sliding up and down. 
     The above-mentioned butt fit refers to a fit being both butted and separated, for instance, under a closing state, the first closing driving surface  623  is in butt joint to the first over-travel leaf spring  13 , and the first disconnecting driving surface  622  may be separated from the first disconnecting side surface  150 . For another example, under a disconnecting state, the first disconnecting driving surface  622  is butt joint to the first disconnecting side surface  150 , and the first closing driving surface  623  may be separated from the first over-travel leaf spring  13 . 
     Referring to  1 ,  3 ,  4 ,  5 ,  7 ,  9  and  10 , the driving end  72  of the second guide transmission part  7  is coupled to the free end  25  of the second movable flat spring  20  through a second elastic transmission structure, and by means of this coupling, the second guide transmission part  7  transfers actions to the free end  25  of the second movable flat spring  20 , and the linear movement of the second guide transmission part  7  is converted into deflecting swing of the free end  25  to drive closing/disconnecting of the second movable contact  27  and the second static contact  27 . Although the second guide mechanism has a favorable function of preventing the slippage, the effect of achieving the result with half effort can be achieved still since the second elastic transmission structure contains a structure of preventing the slippage, in order to further strength the technical effect pursued for the purpose of the present invention. A plurality of specific solutions may be available for the second elastic transmission structure, and may be divided into four implementation forms according to the difference of properties of preventing the driving end  72  of the second guide transmission  7  from swinging up and down. 
     The first solution resides in that: the second elastic transmission structure comprises a second guide sliding surface  721 , a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , as well as a second guide end surface  24 , a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second guide sliding surface  721  is in sliding fit with the second guide end surface  24 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . It is obvious that the sliding fit between the second guide sliding surface  721  and the second guide end surface  24  can further prevent downward slippage of the driving end  72 . In order to further prevent upward slippage of the driving end  72 , the following matched solution may be selected: under the butt joint state during a butt fit process of the second closing driving surface  723  and the second over-travel leaf spring  23  of the second elastic transmission structure, the elastic force F that the second over-travel leaf spring  23  acts to the second closing driving surface  723  includes a component force Fy that drives the second closing driving surface  723  to move downwards. 
     The second solution resides in that: the second elastic transmission structure comprises a second guide sliding surface  721 , a second disconnecting driving surface  722 , a second closing driving surface  723  and a second guide sliding rib  724  that are provided on the driving end  72  of the second guide transmission part  7 , and a second guide end surface  24 , a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , and further comprises a second guide lug  32  that is provided on the base  3 , wherein the second guide sliding surface  721  is in sliding fit with the second guide end surface  24 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 , and the second guide sliding rib  724  is in sliding fit with the second guide lug  32 . It is obvious that the sliding fit between the second guide sliding surface  721  and the second guide end surface  24  can further prevent downward slippage of the driving end  72 , and the sliding fit between the second guide sliding rib  724  and the second guide lug  32  can further prevent upward slippage of the driving end  72 . 
     The third solution resides in that: the second elastic transmission structure comprises a second guide sliding rib  724 , a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , and a second guide lug  32  provided on the base  3 , as well as a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second guide sliding rib  724  is sliding fit with the second guide lug  32 , the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . It is obvious that the sliding fit between the second guide sliding rib  724  and the second guide lug  32  can further prevent upward slippage of the driving end  72 . 
     The fourth solution resides in that: the second elastic transmission structure comprises a second disconnecting driving surface  722  and a second closing driving surface  723  that are provided on the driving end  72  of the second guide transmission part  7 , as well as a second disconnecting side surface  250  and a second over-travel leaf spring  23  that are provided on the free end  25  of the second movable flat spring  20 , wherein the second disconnecting driving surface  722  is in butt fit with the second disconnecting side surface  250 , and the second closing driving surface  723  is in butt fit with the second over-travel leaf spring  23 . It is obvious that such second elastic transmission structure does not comprise a structure of preventing the driving end  72  from sliding up and down. 
     The above-mentioned butt fit refers to a fit being both butted and separated, for instance, under a closing state, the second closing driving surface  723  is in butt joint to the second over-travel leaf spring  23 , and the second disconnecting driving surface  722  may be separated from the second disconnecting side surface  250 ; and under a disconnecting state, the second disconnecting driving surface  722  is in butt joint to the second disconnecting side surface  250 , and the second closing driving surface  723  may be separated from the second over-travel leaf spring  23 . 
     According to the present invention, the base  3  is provided with the guide groove  30 , the two guide transmission parts  6  and  7  are provided with guide ribs and contact guide devices, and when the two guide transmission parts moves leftwards and rightwards, any one of the transmission parts is limited from sliding downwards by means of fit between the contact guide device on the driven end of respective guide transmission part and the guide groove  30  on the base, and any one of the transmission parts is limited from sliding upwards by means of the guide device on the driving end of respective guide transmission part and the guide groove on the base, therefore, the two transmission parts  6  and  7  moves in the horizontal direction furthest to prevent desynchrony of two phases caused by deflection thereof, and therefore and shortening of the contact life. According to the present invention, the contact systems are placed at two sides of magnetic steel, such that the lever ratio of the contacts are increased, and therefore a larger contact pressure can be obtained on the premise that the power consumption of the coil of the product is lower, the action range of the product is expanded, the appearance size of the product is reduced, and therefore the product is more compact and attractive. Referring to  FIGS. 1 and 3 , a non-free end of the first movable flat spring  10  of the first contact device  1  is in U-shaped connection to a first movable connecting plate  11  respectively, namely the first free end  15  of the first movable flat spring  10  forms U-shaped configuration with the first movable connecting plate  11 , and the first over-travel leaf spring  13  is a pressure leaf spring which participates in providing the final pressure of the final pressure for contacts; a non-free end of the second movable flat spring  20  of the second contact device  2  is in U-shaped connection to a second movable connecting plate  21  respectively, namely the second free end  25  of the second movable flat spring  20  forms U-shaped configuration with the second movable connecting plate  21 , and the second over-travel leaf spring  23  is a pressure leaf spring which participates in providing the final pressure for contacts. The movable flat springs are in U-shaped connection with the connecting plates, such that a direction of an electrodynamic force borne by the movable flat spring is a direction away from the movable connecting plate so as to assist in increasing the contact pressure between the movable contacts and the static contacts, and the product can be reliably switched on under a high current by effectively utilizing the electrodynamic force to avoid the burning loss caused by bounce of the contacts. A pressure leaf spring is connected to the movable contact, and the final pressure of the contacts is mainly generated from the deformation of the pressure leaf spring. Pre-pressing over-travel is designed on the movable contacts and the static contacts, such that the pre-pressure is generated during contacting of the movable contacts and the static contacts, to ensure the working reliability of the relay. A plurality of structure solutions may be available for the first movable flat spring  10  of the first contact device  1  and the second movable flat spring  20  of the second contact device  2 , wherein one preferred solution resides in that two groups of movable contacts and static contacts can be provided on each group of contacts respectively, namely referring to  FIG. 12 : two first movable contacts  17  are provided on the first movable flat spring  10 , and correspondingly two first static contacts  16  re provided on the first static connecting plate; and two second movable contacts  27  are provided on the second movable flat spring  20 , and correspondingly two second static contacts  26  are provided on the second static connecting plate, such that the contact surface is increased, the contact resistance and the temperature rise of the contacts are reduced, and the contact resistance reaches below 0.3 mΩ. The above-mentioned embodiments are just recommended embodiments of the present invention, and all the technical equivalent variations and modifications made in accordance to claims of the present invention should be considered to fall into the scope of the present invention.