Abstract:
A framework part of a relay and a relay. An inner hollow portion and peripheral windows are formed by the framework. The windows are communicated with the exterior of the framework and the hollow portion. At least one group of contactors that can correspondingly contact are accommodated in the hollow portion. An arc gap is formed between the contactors that can correspondingly contact. The windows are aligned with the arc gap from an outer side. A main body of the framework is a hollowed injection molding framework, and has multiple windows that are aligned with the arc gap from the outer side, so that, under the precondition of ensuring the structural strength, materials can be reduced and the cost can be reduced. The windows can be used for installing functional components such as magnetic steel, a resistant act clip or an arcing and are extinguishing piece. The framework is made be applicable to relays and breakers having more functions and requirements, so as to improve a scope of application of products to a great extent and facilitate reduction of molds and other manufacturing costs.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to a relay, particularly to a framework of a relay. 
       BACKGROUND 
       [0002]    A relay is a disconnecting or breaking and connecting or closing device that can frequently disconnect or break, carry and connect or close a normal current and a regulated overload current. An existing relay is an electric device that closes the contacts by means of a magnetic field created by a current flowing through a coil, so as to control the load. It is widely used in the fields o electric power, electric distribution, electric consumption, and so on. 
         [0003]    In some alternating current or direct current contactors (relays), a framework main body, a lead terminal portion, a movable spring portion, a magnetic circuit system, and pushing mechanism are generally included. The lead terminal portion includes a lead terminal and a stationary contact; the stationary contact is fixed to the bottom of the lead terminal. The movable contact is fixed to the movable spring piece of the movable spring portion and the movable spring portion is correspondingly located inside the framework main body and is pushed by it pushing mechanism. The stationary contact of the lead terminal portion is matched with the movable contact of the movable spring portion, respectively, so as to achieve closing or breaking of the relay. Here, the main material of the framework main body is plastic. 
         [0004]    However, when the relay is applied for a relatively higher load, i.e., a circuit having a disconnecting or breaking voltage higher than 10V and a current over 100 mA, a conductive gas mass, which is called electric arc, with extremely high temperature and brightness is created m the contact gap (or to say, arc gap). Electric arcs are a type or aerial discharge. In case that the electric arc strikes the plastic material around the contact, the plastic may be carbonized, the insulation property to be decreased sharply, and the relay may be even burned in a serious situation. 
         [0005]    In the prior direct current relays, another solution is that the whole framework is made of a ceramic material, such as the relays in the disclosure of Chinese patent publication CN 102737914A. However, due to the properties of ceramic materials, such framework is typically complex in structure, uncertain in size, and large in weight, and thusly resulting a high cost. 
         [0006]    Such prior relay generally comprises pushing mechanism and a framework portion, the pushing mechanism comprising a movable spring portions, a pushing rod portion, compression spring, a stationary iron core, a movable iron core and a return force spring, wherein the return force spring is mounted between the movable iron core and the stationary iron core. In that case, countersinks are required to be provided in the movable iron core and the stationary iron core, and thusly allowing the both ends of the return for spring to be positioned into the countersinks in the movable and stationary iron cores, respectively. Due to such structure, the opposing magnetic pole area between the movable iron core and the stationary iron core will be decreased, and thusly decreasing the driving force and holding three of the iron cores. In order to keep the driving force and holding force of the iron cores, a larger coil is usually required, resulting an increased cost and increased size of the product. The framework portion typically comprises a lead terminal portion and a framework acting as a current carrying housing. The lead terminal portion is formed by a lead terminal and a stationary contact, and the lead terminal and the stationary contact are fixed with each other by welding. The lead terminal portion is mounted on the framework, the movable spring portion of the pushing, mechanism is accommodated within the framework, and the movable contact of the movable spring portion and the stationary contact of the lead terminal portion are located in matching position. In order to extinguish the arc, a permanent magnet is usually provided all around the framework. The arc is extinguished by means of the permanent magnet. Using the permanent magnet will cause the cost to be increased. Certainly, there is also a solution without any permanent magnets, in which solution the arc is extinguished by increasing the contact gap. In such solution, the contact gap has to be very large, which will lead to the disadvantages that the size of the product is increased and the acting time of the product is lengthened. In addition, welding the lead terminal and the stationary contact may also lead to the disadvantages of high cost and low efficiency. 
       SUMMARY 
       [0007]    A purpose of the present invention is to overcome the defects in the prior art, and to provide a framework of a relay which can achieve a better arc extinguishing without the disadvantages of increased product cost, enlarged product size and elongated product acting time. Also, the framework has the properties of low cost, high efficiency, universality and flexibility. 
         [0008]    A purpose of an aspect of the present invention is to solve the technical problems in the art that the plastic framework is damaged by the arc. 
         [0009]    A purpose of an aspect of the present invention is to solve the technical problems in the art that the full ceramic framework of the relay has a high cost. 
         [0010]    To solve the technical problems, in a technical solution of the present invention there is provided a framework of a relay, is cavity portion is thrilled inside the framework and a window is formed on the periphery of the framework, the window communicates the outside of the framework and the cavity portion; at least one set of contacts that are contactable correspondingly with each other arc accommodated inside the cavity portion; an arc gap is formed between the contacts that are contactable with each other, the window is aligned with the arc gap from outside. 
         [0011]    In another implement there is provided a relay, comprising a lead terminal portion, a movable spring portion, an magnetic circuit portion, a pushing mechanism and a framework portion as above-mentioned, wherein the magnetic portion is connected to a side of the framework portion, the magnetic portion brings the movable contacts on the movable spring portion to act through the pushing mechanism. 
         [0012]    As known from the above description to the present invention, the invention has the following advantages compared with the prior art: 
         [0013]    The main body of the framework is formed as a hollow injection molding framework and has a plurality of windows aligning to the arc gaps from outside, and thusly the material may be saved and cost may be reduces with ensured structure strength. The windows may be used far mounting functional components such as a magnetic steel, an and resistance pieces and an arc attracting and extinguishing pieces. The framework is suitable to be applicable to relays and breakers having more functions and requirements, so as to improve a scope of application of products to a great extent and facilitate reduction of molds and other manufacturing costs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a structural schematic view of a relay framework of a first embodiment of the present invention. 
           [0015]      FIG. 2  is a schematic to view showing the acting principle of the relay framework of the first embodiment of the present invention. 
           [0016]      FIG. 3  a structural schematic view of a relay of the first embodiment of the present invention. 
           [0017]      FIG. 4  is a structural cross-section schematic view of relay framework of a first embodiment of the present invention. 
           [0018]      FIG. 5  is a structural schematic cross-section view of the relay of the first embodiment of the present invention. 
           [0019]      FIG. 6  a structural schematic view of an are resistance piece of the first embodiment of the present invention. 
           [0020]      FIG. 7  is a structural schematic view of another embodiment of an arc resistance piece of the present invention. 
           [0021]      FIG. 8  is a schematic view showing the acting principle of arc blowing of the first embodiment of the present invention. 
           [0022]      FIG. 9  is a schematic to view showing the acting principle of the relay framework of a second embodiment of the present invention. 
           [0023]      FIG. 10  is a schematic top view showing the acting principle of the relay framework of a second embodiment of the present invention. 
           [0024]      FIG. 11  is a schematic view showing the acting principle of arc blowing of the second embodiment of the present invention. 
           [0025]      FIG. 12  is a schematic perspective view showing the structure of a third embodiment of the present invention. 
           [0026]      FIG. 13  is a structural cross-section view of the third embodiment of the present invention. 
           [0027]      FIG. 14  is a schematic perspective view slowing the structure of the framework of the third embodiment of the present invention. 
           [0028]      FIG. 15  is a structural schematic view showing the framework (the bottom surface is turned to the front) of the third embodiment of the present invention. 
           [0029]      FIG. 16  is a schematic view showing the lead terminal portion matched with a first and a second arc extinguishing piece. 
           [0030]      FIG. 17  is a schematic view showing the arc extinguishing principle of the third embodiment of the present invention. 
           [0031]      FIG. 18  is a schematic view showing the acting of the arc extinguishing piece of the third embodiment of the present invention. 
           [0032]      FIG. 19  is a schematic view showing the present invention mounted on a relay. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Features and advantages of the present invention will be apparent from the examplary embodiments in the following description. It is appreciated that the present invention may have various modifications from different embodiments without departing the scope of the present invention, and that the description and drawings therein are intended to be explanatory, rather than limiting the present invention. 
         [0034]    The orientation terms like up, down, top and bottom referred in the present invention are merely used for explain the relative positions of the components, rather than defining the specific mounting orientations of the components of the present invention. 
         [0035]    As show in  FIGS. 1-3 , a first embodiment of the present invention provides a framework of a relay, comprising a lead terminal portion  2 , a framework main body  1 , at least one magnetic steel  4  and at least one are resistance piece  5 . A hollow portion  10  is formed inside the framework main body  1 , the hollow portion  10  comprising a cavity portion  11  therein and one or more window  15  on its periphery. The windows  15  communicate the outside of the framework main body  1  and the cavity portion  11 . The cavity portion  11  accommodates the movable spring portion of the pushing mechanism of the relay. The lead terminal portion  2  comprises a lead terminal  21  and a stationary contact  22 . The stationary contact  22  is fixedly connected to the bottom of the lead terminal  21 . The contacting surfaces of the stationary contact  22  face the cavity portion  11 . 
         [0036]    The stationary contacts  22  on the bottom of the lead terminal portion  2  correspond to and match with the movable contacts  31  of the movable spring portion  3  respectively (see  FIG. 4 ). The stationary contacts  22  may correspond to and contact with the movable contacts  31 , and an arc gap A is formed therebetween. Each of the windows  15  may be aligned with the arc gap A from outside (see  FIG. 4 ). As described here, the corresponding and contacting contacts may be a set of electric contacts that can contact with each other, and also, may be two or more sets, each set of the contacts comprises as movable contact  31  and a stationary contact  22 . The gaps for are burning between the contacts are arc gaps A which may be smaller than the maximum gap between the contacts. 
         [0037]    The magnetic steel  4  may be mounted to the window  15  of the framework main body  1 . The magnetic steel  4  is located on the periphery of the cavity portion  11 . The magnetic steel  4  may perform arc blowing to the are created when breaking contact in the arc gap A inside the cavity portion  11 . The arc resistance piece  5  is mounted to the window  15  of the framework main body  1 , and is located on the are blowing direction of the magnetic steel  4 . In the case that the contacts are multiple sets, the form of the corresponding framework main body is not limited to the shape as shown in the figures, and the arc resistance piece  5  and magnetic steels  4  may be increased correspondingly in sets. The expression that the resistance are piece  5  is located “on the arc blowing direction of the magnetic steel  4 ” means, under the magnetic field of the magnetic steel  4 , the are at the arc gap A is blown towards the periphery direction, and the arc resistance piece  5  can block the arc blown by the magnetic steel  4  so as to extinguish the arc and lower the temperature. In a better method, for easier mounting, a ceramic piece  5  may be also arranged symmetrically with its center aligned with that of the arc gap A. 
         [0038]    When the relay is applied for a relatively higher load, it the arc strike on the plastic around the contacts, the plastic may be carbonized and the insulation property may be decreased sharply. In order to avoid this, in an embodiment of the present invention, an arc resistance piece  5  that can resistant high temperature, such as a ceramic piece, is mounted symmetrically close to the arc gap A. The arc resistance material has the effect of cooling the arc, improves the reliability and electric life of the product, has a cost lower than that of a framework entirely made of ceramic material, and may make the structure of the framework more concise. Here, the magnetic steel  4  is the arc blowing device, and certainly, an electromagnetism arc blowing device or other arc blowing devices may be used. 
         [0039]    In particular, the first embodiment is shown in  FIG. 1 . The framework main body  1  has a general hollow cuboid shape. The framework main body  1  is made of plastic and comprises a plurality of posts  12 , an upper mounting portion  13  and a lower connection portion  14 . Each of the posts  12  arc arranged separately OP the periphery of the hollow portion  11 , the windows  15  of opening type is formed between the adjacent posts  12 . The upper mounting portion  13  is connected to each of the posts  12  on the upper portion. A connection plate  133  as a main body of the upper mounting portion  13  has a fixing portion  131  protruding from the top portion thereof. The fixing portion  131  has rounded shapes on its both ends, and two positioning holes  132  having a distance therebetween are formed on the fixing portion  131 , the positioning holes  132  are stepped holes such that the lead terminal portion  2  of the relay can be fixed. The lower connection portion  14  is connected to each of the posts  12  on the lower portion. In the present embodiment, the lower connection portion  14  is an elongated plate piece connected between the posts  12 , and is provided with a snapping portion  141  so as to be fixedly connected to a magnetic circuit system  6 . Certainly, a screwing portion or a riveting portion can be used to achieve the above connection. 
         [0040]    The framework main body  1  is a hollow framework and has a plurality of windows  15  being aligned to the are gaps from outside, which allows saving materials and lowering costs with ensured structure strength. 
         [0041]    Here, as shown in  FIG. 2 , the contactable contacts are two separated groups, corresponding to two separated arc gaps A. The contacts consist of movable contacts  31  located correspondingly inside the cavity portion  11  and stationary contacts  22  fixed to the upper portion inside the framework main body  1 . The movable contacts  31  may be driven by a pushing mechanism so as to contact/break from the stationary contacts  22 . 
         [0042]    In the first embodiment as shown in  FIGS. 1, 2 and 4 , the positions of the windows are aligned with the arc gaps A from outside. Two magnetic steels  4  are mounted respectively on the windows  15  on the extension line extending from a connecting line between the two arc gaps A. Here, the referred “connecting line between the two arc gaps A” may be a connecting line between the center points. The magnetic steels  4  may be embedded into the framework main body without any additional fixing components and any mounting space for the fixing components, so as to decrease the outline size of the product. And the magnetic steels may be very close to the contacts, which will be advantageous to increase the magnetic field density passing through the contacts so as to improve the arc blowing capacity. Two pairs of arc resistance pieces  5  are mounted to the two windows  15  outside the are gaps, respectively. The connecting line between the centers of two corresponding resistant arc pieces  5  is perpendicular to the connecting line between the two arc gaps A. 
         [0043]    The high temperature resistance material of the are resistance pieces  5  may be PET/GF antiflaming arc resistance composite materials, composite polytef arc resistance material; heat and arc resistance organosilicon plastic or ceramic pieces. In the materials as above, the ceramic pieces has low cost and stable properties, and the are resistance pieces  5  in an embodiment of the present invention are thusly made of ceramic material. As shown in  FIGS. 6 and 7 , at lease one edge of the arc resistance piece  5  extends along an edge of the corresponding window  15  to form an inside extension portion  52 . The arc resistance piece  5  forms a L-shaped right angled shape. Since the arc has a cylindrical shape in operation and will moves along a parabola to a side under the magnetic blowing of the magnetic steel  4 , the right angled ceramic piece may increase the protection range. As shown in  FIG. 7 , the top surface, bottom surface or two sides of the arc resistance piece  5  may partially protrude outside to form a protruding block  51  or a recess block. 
         [0044]    Limit ribs  151  may be formed at the position on the windows  15  where the arc resistance pieces  5  are mounted. Both ends of the limit ribs  151  are connected to the posts  12  on both sides. The shape of the limit ribs  151  fit the shape of the arc resistance piece  5 . As shown in  FIGS. 1-3 , middle portion of the limit rib  151  has a U-shaped recess, and the limit rib  151  has a snapping strip on a surface contacting with the edge of the arc resistance piece  5  inside the recess. The snapping strip has a slope tightly snapping the edge of the arc resistance piece  5  from outside to inside. A clamping portion is formed accordingly on the mounting positions of each of the windows  15 . The arc resistance piece  5  is mounted to the framework main body  1  by snapping or embedding. At the same time, a housing of the product presses against the arc resistance piece  5  from outside, so as to position the are resistance piece  5  from six directions. 
         [0045]    The arc resistance piece  5  may be fixed by, besides the above-mentioned manner, integrally injected together with the framework main boy, or snapped into the framework main body by an up-down slot, and so on. 
         [0046]    With reference to the schematic diagram of  FIG. 8 , two magnetic steels  4  are mounted on the extension line extending outside from the connecting line between the two arc gaps. There is no requirement for the magnetic poles of the two magnetic steels, but preferably, the opposite surfaces of the two magnetic steels have reversed magnetic poles. The direction of the magnetic lines is perpendicular to that of the arc created by the contacts. In this way, when an arc is created between the contacts, the two magnetic steels  4  can blow the arc to both sides. Even if the current in the two contacts change their direction, the arc will still be blown to a side, and even if the magnetic poles of the two magnetic steels  4  arc wrongly mounted, the arc will still be blown to a side, and thusly the safety of the product will be still ensured. In the present embodiment, the framework is provided with magnetic steels symmetrically on both sides. In this way, when an arc is created between the contacts, the two magnetic steels will blow the arc form two side directions. Even if the current in the two contacts change their direction, the magnetic blowing direction will still be directed to a side, And even if the magnetic poles of the two magnetic steels are mounted improperly, the magnetic blowing direction is still directed to a side, and the safety of the product is still ensured. 
         [0047]    Certainly, in a second embodiment as shown in  FIGS. 9-11 , a pair of arc resistant pieces  5  may be mounted to the windows  15  on the extension line extending outwardly from the connecting line between the two arc gaps A, and the magnetic steel  4  may be mounted on the two windows  15  outside the are gaps A, the connecting line between the centers of the two corresponding magnetic steels is perpendicular to the connecting line between the two arc gaps A. Similarly, the arc resistance piece  5  is positioned on the blowing direction of the magnetic steel  4 . In this case, according to the flow direction of the current, the poles of the four magnetic steels should be arranged in two manners as shown in  FIG. 11 , the opposing surfaces of opposing magnetic steels should have reversed polarity. According to the left-hand rule in electromagnetism, one flatten his hand and let the magnetic lines to pass through his palm, his thumb being perpendicular to the other four fingers and in the same plane with the palm. When the left hand is put into the magnetic field, with the magnetic lines passing through the palm perpendicularly, the palm facing the N pole, and the four fingers being oriented in the direction of the current, the direction of the thumb will be the direction of force. When an arc is created in the magnetic field, the force acting thereon will follow the left-hand rule, and the force on the arc acted by the magnetic steel will be directed outwards. 
         [0048]    An embodiment shown in  FIGS. 3-5  is the above-mentioned embodiment applied on a relay. Generally, the relay further comprises a lead terminal portion  2 , a movable spring portion  3 , a magnetic circuit system  6 , a housing  7  and a pushing mechanism  8 . The lead terminal portion  2  comprises a lead terminal  21  and a stationary contact  22 . The stationary contact  2 . 2  is fixedly connected to the bottom of the lead terminal  21 , for example, by riveting manner. The contacting surface of the stationary contact  22  faces a cavity portion  11 . A movable contact  31  is fixedly mounted to a movable spring  32  of the movable spring portion  3 , and located correspondingly into the cavity portion  11 . The pushing mechanism  8  is driven by the magnetic circuit system  6  and drives the movable spring portion  3  to move. The pushing mechanism  8  comprises a pushing rod  81 , a limit elastomer  82 , an isolation sheath  83 , and so on. The main body of the pushing rod  81  is mounted in a coil  62  of the magnetic circuit system  6  with its one end extending outwards to be fixed to the isolation sheath  83 . The limit elastomer  82  is a spring. An upper end surface of the movable spring portion  3  abuts the isolation sheath  83 , and a lower end surface of the movable spring portion  3  is fixed by the fitting of the isolation sheath  83  and the positioning spring  82 . The magnetic circuit system  6  is moved by the pushing mechanism  8  driving the movable spring portion  3 . The closing or breaking of the relay is achieved b the corresponding fittings of the stationary contacts  22  of the two lead terminal portion  2  with the movable contacts  31  of the movable spring portion  3 , respectively. 
         [0049]    The arc resistance material in the above-mentioned embodiment of the present invention has the effect of cooling the arc, improves the reliability and electric life of the product, has a cost lower than that of a framework entirely made of ceramic material, and may make the structure of the framework more concise. 
         [0050]    As shown in  FIGS. 12-19 , likewise, a framework portion of a relay of a third embodiment of the present invention comprises a lead terminal portion  2  and a framework main body  1 . The lead terminal portion  2  comprises a lead terminal  21  and a stationary contact  22 . The stationary contact  22  is fixedly connected to the bottom of the lead terminal  21 . The framework main body  1  is provided with a hollow portion  10  for accommodating a movable spring  3  of a pushing mechanism of the relay. The two lead terminal portions  2  are mounted respectively to the top of the hollow portion  10  of the framework, allowing the stationary contacts  22  of the two lead terminal portions to correspondingly fit the movable contacts  31  of the movable spring portion  3 . The differences between the first and second embodiments be in that the windows  15  on both sides of the hollow portion  10  of the framework main body  1  are provided symmetrically with a plurality of slots  16 . Said slots  16  are arranged from up to down, and both ends of the plurality of slots  16  communicate with the outside of the framework main body  1  and the hollow portion  10  of the framework, respectively. 
         [0051]    Said plurality of slots  16  are arranged with distances in a direction from up to down. 
         [0052]    The framework further comprises two first arc extinguishing pieces  17  and at least two second are extinguishing pieces  18 . Said two first arc extinguishing pieces  17  are symmetrically mounted into the slots  16  in the uppermost layer on both sides of the framework, respectively, and the two first arc extinguishing pieces  17  are close to or abut against the corresponding lead terminal portions  2 , respectively. Said at least two second arc extinguishing pieces  18  are symmetrically mounted into the corresponding slots  16  on both sides of the framework, respectively, and located below and adjacent to the first arc distinguishing pieces  17 . The second arc extinguishing pieces  18  have a length smaller than that of the first arc extinguishing pieces  17 , such that there are distances between the second are extinguishing pieces  18  and the lead terminal portions in the projection plane. In this embodiment, there are four second arc extinguishing pieces  18 . Each sides of the framework main body  1  is mounted with two second arc extinguishing pieces  18 . 
         [0053]    Said first arc distinguishing pieces  17  and second arc extinguishing pieces  18  are each provided with an opening facing the inside of the framework. That is, the first arc distinguishing pieces  17  are provided with openings  171  facing the inside of the framework, and likewise, the second arc distinguishing pieces  18  are provided with openings (not shown in the figures) facing the inside of the framework. 
         [0054]    Said openings  171  of the first are distinguishing pieces  17  is close to or abut against the corresponding lead terminal portion  2 . 
         [0055]    Said openings  171  of the first arc distinguishing pieces  17  may have a Y-shape, and certainly may have a V-shape. Likewise, the openings of the second arc distinguishing pieces  18  have a Y-shape. 
         [0056]    Said openings  171  of the first are distinguishing pieces  17  is close to or abut against the stationary contacts  22  of the corresponding lead terminal portions. 
         [0057]    A recess for placing a return force spring of the pushing mechanism is also provided on the top of the hollow portion of said framework, so as to provide a return force for the pushing mechanism. 
         [0058]    The bottom of the lead terminals and said stationary contacts are fixed with each other by riveting. 
         [0059]    A recess  19  for placing a return Mice spring of the pushing mechanism is also provided on the top of the hollow portion of said framework main body  1 , so as to provide a backward force for the pushing mechanism. 
         [0060]    The bottom of the lead terminals  21  and said stationary contacts  22  are fixed with each other by riveting. 
         [0061]    The third embodiment of the present invention provides a framework portion of a relay, wherein a plurality of slots  16  are provided symmetrically on both sides of the framework. The plurality of slots are arranged from up to down, and both ends of the plurality of slots  10  communicate with the outside of the framework main body  1  and the hollow portion  10  of the framework, respectively. In this way, an are extinguishing pieces may be selected to be used or not used according to different loads. In the case of a small load, the arc extinguishing piece may be not used, and the arc is extinguished by a contact gap; in the case that the arc extinguishing pieces is needed, besides using a first are extinguishing piece  17 , different numbers of second arc extinguishing pieces may be selected and used according to different load, so as to achieve a best arc extinguishing effect, and has universality and flexibility. In this embodiment, first arc extinguishing pieces  17  are inserted into the slots  16  in an uppermost layer on both sides of the framework, and two first arc extinguishing pieces  17  are close to or abut against the contacts  12  of the corresponding lead terminal portions, respectively, forming unipotential positions with the contacts  12 , so as to perform arc extinguishing, and avoid the disadvantage caused by arc extinguishing with permanent magnetic or enlarged contact gap as done in the prior art. A better arc extinguishing effect may be achieved without the disadvantages of increased cost, enlarged product size and prolonged product acting time. In this embodiment, the arc extinguishing is also achieved by inserting one or more second arc extinguishing pieces  18  under the first arc extinguishing pieces  17  on both sides of the framework, the second arc extinguishing pieces  18  are cooperated with the first arc extinguishing pieces. The one or more second arc extinguishing pieces  18  are arranged with distances therebetween under the first arc extinguishing pieces  17 , so as to divide the are into a lot of short arcs a (as shown in  FIG. 17 ) to extinguish the arc. In this embodiment, each of the first arc extinguishing pieces  17  and second arc extinguishing pieces  18  is provided with an opening facing the inside of the framework, and each of the openings of the first arc extinguishing pieces and second arc extinguishing pieces has a Y shape (may be a V shape instead). Due to this structure, the magnetic circuit path created by the are current in surrounding spaces is deformed, thereby an attraction force F (as shown in  FIG. 18 , the letter B in  FIG. 18  indicating the magnetic path) is created to bring the arc b to the arc extinguishing pieces, so as to achieve better arc attraction and extinguishing fleets. In this embodiment, a recess  19  for placing the return force spring is provided on a top of a hollow portion of the framework for providing a return force for the pushing mechanism, which eliminate the disadvantage in the prior art caused by the return force spring placed between the movable iron core and the stationary iron core. In this embodiment, the stationary contacts  22  and lead terminals  21  are fixed by riveting, which may red ace cost and improve efficiency. 
         [0062]    Although the present invention has been described with respective to several exemplary embodiments, it should be appreciated that the terms used are intend to illustrative and exemplary, rather than limiting terms. Since the present invention can be specifically implemented in various manners without departing the spirit or substance thereof, it should be appreciated that the abovementioned embodiments are not limited to any aforementioned details, and should be explained broadly within the spirit and scope defined by the appending claims. Therefore, all the variations and modifications in the scope of the claims and its equivalents should be covered by the claims.