Patent Publication Number: US-9837233-B2

Title: Rotating dual break point contact

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a national stage application based on PCT/US2014/086919, filed on Sep. 19, 2014, which claims the priority of Chinese Patent Application No. 201310459310.5, filed on Sep. 24, 2013. This application claims the benefit and priority of these prior applications and incorporates their disclosures by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to contact structure of a circuit breaker, more particularly, relates to a moving contact module in a circuit breaker. 
     2. The Related Art 
     Dual break point form is a trend of molded case circuit breakers. Contact module is an important part of a molded case circuit breaker and has drawn attention in the field. Modern molded case circuit breakers with high breaking capability mainly use rotating dual break point contacts. The rotating dual break point contacts have a lot of different structures. Some products also provide additional functions such as a lock function to lock the contact after the contact is repulsed by an electro-dynamic repulsion force, so that the contact will not rebound back. 
     The Chinese patent application with the application number CN201110310339.8 discloses a rotating dual break point moving contact module. The moving contact may open quickly under large short circuit current, the moving contact will be locked after opening and will not rebound. The moving contact module also keeps balance of contact pressure on different sides. The rotating dual break point moving contact module disclosed in CN201110310339.8 has two contact springs. The two contact springs are arranged on both sides of the contact module so that the width dimension of the module is large. The large width dimension is unfavorable to miniaturization, especially when a plurality of contact modules need to be cascaded to form a multi-phase contact module, the width dimension will be a key parameter that may affect the overall volume of the multi-phase contact module. 
     SUMMARY 
     The present invention provides a rotating dual break point contact with a compact structure and small volume. 
     According to an embodiment of the present invention, a rotating dual break point contact is provided. The contact comprises a rotor support, a first shaft, a second shaft, a third shaft, a first connection rod, a second connection rod, a contact bridge and a contact spring. The contact bridge is provided in the rotor support, the contact bridge rotates relative to the rotor support by means of the first shaft, the second shaft, the third shaft, the first connection rod and the second connection rod. The contact bridge rotates between an initial pressure position and a maximum repulsion position. A single contact spring is mounted on one side of the contact bridge and is located in the rotor support. 
     The rotor support is single phase independent. The rotor support comprises two side plates and two lateral shafts which connect the two side plates, the two side plates are uniform in shape and size. The two side plates have a gap therebetween which is sufficient for the contact bridge to pass through. The two lateral shafts are centrosymmetric. Each side plate is provided with a central hole in the center, each side plate is provided with a pair of centrosymmetric linkage holes and a pair of centrosymmetric connection slots. The pair of linkage holes are disposed on two ends of the major axis of the side plate respectively, and the pair of the connection slots are disposed on two ends of the minor axis of the side plate respectively. 
     Two first connection rods are mounted between the two side plates and are arranged on different sides of the contact bridge. The first connection rod is provided with a short shaft, the short shaft is mounted in the connection slot, the short shaft is the rotation center of the first connection rod. 
     Two second connection rods are mounted between the two side plates and are arranged on different sides of the contact bridge. 
     The contact bridge is centrosymmetric in cross section. The contact bridge is provided with an obround hole in the center, the first shaft passes through the obround hole and slides therein along a longitudinal direction of the obround hole. The first shaft is the rotation center of the contact bridge when the first shaft slides to one end of the obround hole. The contact bridge is provided with a pair of centrosymmetric curved surfaces and a pair of centrosymmetric through holes. Two curved surfaces cooperate with two lateral shafts to constrain the rotation range of the contact bridge. Two third shafts pass through two through holes respectively. The contact bridge is provided with two contact points on each side, the two contact points are welded to a contact. The longitudinal direction of the obround hole and a line connecting the two contact points form an included angle, the included angle keeps balance of the contact pressure of the contact points on both sides of the contact bridge. 
     The first shaft passes through the obround hole on the contact bridge and the central hole on the side plate. 
     Two second shafts respectively pass through the first connection rod and the second connection rod and are mounted on profile of the two side plates, the two second shafts are arranged centrosymmetrically. 
     Two third shafts respectively pass through the through hole on the contact bridge and the second connection rod. The two third shafts are arranged centrosymmetrically. 
     Two ends of the single contact spring are mounted on two second shafts respectively. 
     According to an embodiment, the central holes on the two side plates are aligned, the linkage holes on the two side plates are aligned, the connection slots on the two side plates are aligned. The first shaft cooperates with the central hole by means of a minuteness gap. 
     According to an embodiment, a cylindrical surface on the lateral shaft cooperates with the curved surface on the contact bridge, two lateral shafts correspond to the initial pressure position and the maximum repulsion position of the contact bridge respectively, the cylindrical surface on the lateral shaft cooperates with the curved surface by means of a minuteness gap. 
     According to an embodiment, the first connection rod comprises a body and two terminal surfaces laterally extending from both ends of the body. Each terminal surface is provided with a convex short shaft and a first shaft hole, the short shaft and the first shaft hole are symmetric about the body on the terminal surface. The short shaft cooperates with the connection slot by means of a minuteness gap. 
     According to an embodiment, the second connection rod comprises a body and two terminal surfaces laterally extending from both ends of the body. Each terminal surface is provided with a second shaft hole and a third shaft hole. The second shaft hole and the third shaft hole are symmetric about the body on the terminal surface. 
     According to an embodiment, the side plate is provided with a groove slot. The second shaft passes through the first shaft hole on the first connection rod and the second shaft hole on the second connection rod. The second shaft is mounted on the groove slot. The second shaft cooperates with the first shaft hole and the second shaft hole by means of minuteness gaps respectively. 
     According to an embodiment, the third shaft passes through the third shaft hole on the second connection rod. The third shaft cooperates with the third shaft hole by means of a minuteness gap. 
     According to an embodiment, the rotor support is provided with a connection rod slot and a spring slot on both side plates. A depth of the connection rod slot is not smaller than a thickness of the body of the first connection rod. The body enters into the connection rod slot when the first connection rod rotates, the contact spring is able to move in the spring slot. 
     According to an embodiment, a plurality of contact modules with the rotating dual break point contact are cascaded to form a multi-phase contact module. A linkage shaft is mounted in the linkage holes to realize linkage of the multi-phase contact module. 
     The rotating dual break point contact of the present invention has a simple structure and high reliability. The contact pressure on both sides of the contact bridge is balanced via an included angle between an obround hole and contact points. A single spring is utilized so that the rotating dual break point contact has a compact structure and small volume. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features, natures, and advantages of the invention will be apparent by the following description of the embodiments incorporating the drawings, wherein: 
         FIG. 1  illustrates an assembling structure diagram of a rotating dual break point contact according to an embodiment of the present invention. 
         FIG. 2  illustrates the structure of a contact bridge in a rotating dual break point contact according to an embodiment of the present invention. 
         FIG. 3  illustrates the structure of a first connection rod in a rotating dual break point contact according to an embodiment of the present invention. 
         FIG. 4  illustrates the structure of a second connection rod in a rotating dual break point contact according to an embodiment of the present invention. 
         FIG. 5  illustrates a schematic diagram of a multi-phase contact module formed by cascading of a plurality of rotating dual break point contacts according to an embodiment of the present invention. 
         FIG. 6  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at an open position or a release position. 
         FIG. 7  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a close position. 
         FIG. 8  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a dead point. 
         FIG. 9  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a maximum repulsion position. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The Chinese application with the application number CN201110310339.8 was also filed by the applicant of the present application. The present invention is carried out based on CN201110310339.8, with miniaturized volume and simplified structure. The present invention discloses a repulsion and lock apparatus with less components, simpler structure and higher reliability. When a contact bridge is repulsed with a small angle by an electro-dynamic repulsion force, a lock component may quickly lock the contact bridge at a maximum repulsion position. Another problem that a rotating dual break point contact shall face to is to keep balance of contact pressure on different sides of the contact bridge. The present invention may increase the stability of the pressure balance between the contacts on different sides of the contact bridge, while maintaining the contact pressure at a desired level. The basic operating principle of the present invention is similar to CN201110310339.8 and the basic operating principle will not be repeatedly described here. A difference between the present invention and CN201110310339.8 is that the present invention utilizes a single contact spring. Single contact spring structure may significantly reduce the dimension of width of the structure. The saved space may be used to thicken shells of a circuit breaker so as to increase mechanical strength, therefore breaking reliability of the circuit breaker is enhanced. Single contact spring structure may also reduce volume of the circuit breaker to realize a miniaturized product. A single contact spring may be disposed within a rotor support, which may prevent the contact spring from damage of arc or metal particles. 
     The present invention provides a rotating dual break point contact. The contact comprises: a rotor support  102 , a first shaft  103 , a second shaft  104 , a third shaft  105 , a first connection rod  106 , a second connection rod  107 , a contact bridge  108  and a contact spring  109 . The contact bridge  108  is provided in the rotor support  102 . The contact bridge  104  rotates relative to the rotor support  102  by means of the first shaft  103 , the second shaft  104 , the third shaft  105 , the first connection rod  106  and the second connection rod  107 . The contact bridge  108  rotates between an initial pressure position and a maximum repulsion position. A single contact spring  109  is mounted on one side of the contact bridge  108  and is located in the rotor support  102 . 
     As shown in  FIG. 1 ,  FIG. 1  illustrates an assembling structure diagram of a rotating dual break point contact according to an embodiment of the present invention. The rotor support  102  is single phase independent. The rotor support  102  comprises two side plates  121  and two lateral shafts  122  which connect the two side plates. The two side plates  121  are uniform in shape and size, the two side plates  121  have a gap therebetween which is sufficient for the contact bridge  108  to pass through. The two lateral shafts  122  are centrosymmetric. Each side plate is provided with a central hole  131  in the center, each side plate is provided with a pair of centrosymmetric linkage holes  132  and a pair of centrosymmetric connection slots  134 . The pair of linkage holes  132  are disposed on two ends of the major axis of the side plate respectively, and the pair of the connection slots  134  are disposed on two ends of the minor axis of the side plate respectively. The central holes  131  on the two side plates  121  are aligned, the linkage holes  132  on the two side plates  121  are aligned, and the connection slots  134  on the two side plates  121  are aligned, so that the shafts may pass through the holes or slots. 
     Two first connection rods  106  are mounted between the two side plates  121  and are arranged on different sides of the contact bridge  108 . The first connection rod  106  is provided with a short shaft  163 , which is mounted in the connection slot  134 . The short shaft  163  is the rotation center of the first connection rod  106 .  FIG. 3  illustrates the structure of a first connection rod in a rotating dual break point contact according to an embodiment of the present invention. The first connection rod  106  comprises a body and two terminal surfaces laterally extending from both ends of the body. Each terminal surface is provided with a convex short shaft  163  and a first shaft hole  164 . The short shaft  163  and the first shaft hole  164  are symmetric about the body on the terminal surface. The short shaft  163  cooperates with the connection slot  134  by means of a minuteness gap. The rotor support  102  is provided with a connection rod slot and a spring slot on both side plates  121 . A depth of the connection rod slot is not smaller than a thickness of the body of the first connection rod  106 . The body enters into the connection rod slot when the first connection rod  106  rotates. 
     Two second connection rods  107  are mounted between the two side plates  121  and are arranged on different sides of the contact bridge  108 .  FIG. 4  illustrates the structure of a second connection rod in a rotating dual break point contact according to an embodiment of the present invention. The second connection rod  107  comprises a body and two terminal surfaces laterally extending from both ends of the body. Each terminal surface is provided with a second shaft hole  171  and a third shaft hole  172 . The second shaft hole  171  and the third shaft hole  172  are symmetric about the body on the terminal surface. 
     The contact bridge  108  is centrosymmetric in cross section. The contact bridge is provided with an obround hole  182  in the center, the first shaft  103  passes through the obround hole  182  and slides therein along a longitudinal direction of the obround hole. The first shaft  103  is the rotation center of the contact bridge  108  when the first shaft  103  slides to one end of the obround hole. The contact bridge is provided with a pair of centrosymmetric curved surfaces  181  and a pair of centrosymmetric through holes  183 . Two curved surfaces  181  cooperate with two lateral shafts  122  to constrain the rotation range of the contact bridge  108 . Two third shafts  105  pass through two through holes  183  respectively. The contact bridge  108  is provided with two contact points on each side, the two contact points are welded to a contact. The longitudinal direction of the obround hole  182  and a line connecting the two contact points form an included angle, which keeps balance of the contact pressure of the contact points on both sides of the contact bridge  108 .  FIG. 2  illustrates the structure of a contact bridge in a rotating dual break point contact according to an embodiment of the present invention. A cylindrical surface on the lateral shaft  122  cooperates with the curved surface  181  on the contact bridge  108 . Two lateral shafts  122  correspond to the initial pressure position and the maximum repulsion position of the contact bridge  108  respectively. The cylindrical surface on the lateral shaft  122  cooperates with the curved surface  181  by means of a minuteness gap. 
     The first shaft  103  passes through the obround hole  182  on the contact bridge  108  and the central hole  131  on the side plate  121 . The first shaft  103  cooperates with the central hole  131  by means of a minuteness gap. 
     Two second shafts  104  respectively pass through the first connection rod  106  and the second connection rod  107  and are mounted on profile of the two side plates  121 . The two second shafts  104  are arranged centrosymmetrically. The side plate  121  is provided with a groove slot  135 . The second shaft  104  passes through the first shaft hole  164  on the first connection rod  106  and the second shaft hole  171  on the second connection rod  107 . The second shaft  104  is mounted on the groove slot  135 . The second shaft  104  cooperates with the first shaft hole  164  and the second shaft hole  171  by means of minuteness gaps respectively. 
     Two third shafts  105  respectively pass through the through hole  183  on the contact bridge and the second connection rod  107 . The two third shafts  105  are arranged centrosymmetrically. The third shaft  105  passes through the third shaft hole  172  on the second connection rod  107 . The third shaft  105  cooperates with the third shaft hole  172  by means of a minuteness gap. 
     Two ends of the single contact spring  109  are mounted on two second shafts  104  respectively. The rotor support  102  is further provided with a spring slot on both side plates  121 . The contact spring  109  is able to move in the spring slot. It should be noted that, because only a single contact spring  109  is used in the present invention, the single contact spring  109  is arranged in one spring slot on one side plate  121 . Both side plates  121  are provided with spring slots so that the arrangement of the contact spring is more flexible, and the contact spring may be arranged in either side. 
       FIG. 5  illustrates a schematic diagram of a multi-phase contact module formed by cascading of a plurality of rotating dual break point contacts according to an embodiment of the present invention. As shown in  FIG. 5 , a plurality of contact modules with the described rotating dual break point contact are cascaded to form a multi-phase contact module. A linkage shaft  150  is mounted in the linkage holes  132  to realize linkage of the multi-phase contact module. 
     According to the embodiments of the present invention, the rotating dual break point contact utilizes a single spring structure so that the axial dimension of the spring structure is dramatically reduced. Then the axial dimension of the contact module shell and the linkage shaft may be increased so as to increase the overall strength of the contact module. 
     The operating process and operating principle of the present invention are as follows: when a circuit break is at an open position, a mechanism formed by connection rods and shafts rotates clockwise under a spring force of the contact spring. The force is transferred to the first connection rod via the first shaft and the first shaft rotates clockwise. Meanwhile, the force is transferred to the contact bridge via a four rod linkage mechanism formed by the first connection rod, the second connection rod and the contact bridge. The contact bridge rotates clockwise and curved surface on the contact bridge contacts with the cylindrical surface on the lateral shaft of the rotor support. The circuit breaker is set to an open status. The circuit breaker shall have a similar status at a release position, so the release position will not be further described here.  FIG. 6  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at an open position or a release position. 
     When a circuit breaker is at a close position, the mechanism formed by connection rods and shafts rotates anti-clockwise under a spring force of the contact spring. The force is transferred to the first connection rod via the first shaft and the first shaft rotates anti-clockwise. Meanwhile, the force is transferred to the contact bridge via a four rod linkage mechanism formed by the first connection rod, the second connection rod and the contact bridge. The contact bridge rotates anti-clockwise and the contacts on the contact bridge (the moving contacts) contact with static contacts.  FIG. 7  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a close position. 
     When large current passes through a circuit breaker, the contact bridge rotates clockwise very fast under an electro-dynamic repulsion force generated between contacts. When the electro-dynamic repulsion force is large enough, the contact bridge rotates clockwise and goes over a dead point of the circuit breaker.  FIG. 8  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a dead point. The first connection rod receives a spring force during the rotation, when the contact bridge rotates over the dead point, the spring force received by the first connection changes is direction from anti-clockwise to clockwise. The clockwise spring force is transferred to the contact bridge via the four rod linkage mechanism formed by the first connection rod, the second connection rod and the contact bridge. The clockwise rotation of the contact bridge is accelerated by the spring force to make the contact bridge leave away from static contacts. The contact bridge finally reaches the maximum repulsion position, backside of the profile of the contact bridge contacts with the lateral shaft on the rotor support, or in other words, the curved surface on the contact bridge contacts with the cylindrical surface on the lateral shaft. The circuit breaker is broken.  FIG. 9  illustrates a schematic diagram of a rotating dual break point contact according to an embodiment of the present invention, wherein a circuit breaker is at a maximum repulsion position. The rotating dual break point contact may break the circuit breaker without an action of the operation mechanism, so that a minimal breaking time of a circuit breaker may be reduced significantly. 
     According to the embodiments of the present invention, the rotating dual break point contact comprises two contact structures on different sides of the contact bridge, the two contact structures shall be centrosymmetric. However, when the two contact structures are no longer centrosymmetric due to dimension or position deviation, the contact bridge shall have a self-adjustment ability so as to keep balance of the contact pressure on both sides and maintain the contact pressure at a desired level. The self-adjustment ability of the contact bridge is realized by providing the contact bridge with high degrees of freedom in a plane perpendicular to an axial of the rotor support. The obround hole in the contact bridge allows the rotation center of the contact bridge be deviated from the rotation center of the rotor support. The rotation center of the contact bridge may shift along the longitudinal direction of the obround hole so that the contact pressure on different sides is adjusted. The amount of adjustment is determined by an angle between the longitudinal direction of the obround hole and a welding surface of the contacts. The angle may be changed within a range where the welding surface is parallel to the longitudinal direction and the welding surface is perpendicular to the welding surface. The contact pressure difference between two sides presents a normal distribution, which means that an optimal equilibrium point exists. At the optimal equilibrium point, the contact bridge may have the best adjusting ability for balancing the contact pressure on different sides. 
     The rotating dual break point contact of the present invention has a simple structure and high reliability. The contact pressure on both sides of the contact bridge is balanced via an included angle between an obround hole and contact points. A single spring is utilized so that the rotating dual break point contact has a compact structure and small volume. 
     The above embodiments are provided to those skilled in the art to realize or use the invention, under the condition that various modifications or changes being made by those skilled in the art without departing the spirit and principle of the invention, the above embodiments may be modified and changed variously, therefore the protection scope of the invention is not limited by the above embodiments, rather, it should conform to the maximum scope of the innovative features mentioned in the Claims.