Abstract:
An operating mechanism controls and trips a separable contact structure arranged in a protected circuit. The mechanism includes a frame, a drive member pivotally coupled to the frame, a spring pivotally connecting the drive member to a drive connector, an upper link pivotally seated on the drive connector, a lower link member pivotally coupled to the drive connector, a crank member pivotally coupled to the lower link member for interfacing the separable contact structure, and a cradle member pivotally secured to the frame and pivotally securing the upper link. The cradle member is configured for being releasably engaged by a latch assembly, which is displaced upon occurrence of a predetermined condition in the circuit such as a trip condition. The mechanism is movable between a tripped position, a reset position, an off position, and an on position. Spacers are operatively positioned between movable members, and protrusions are operatively formed on the enclosure of the contact structure. The spacers and protrusions serve to widen the stances of the operating mechanism for force distribution purposes, and also to minimize friction between movable components.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This Application is a divisional application of U.S. application Ser. No. 09/516,475 filed Mar. 1, 2000, which is hereby incorporated by reference in its entirety. 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    The present invention is directed to circuit interrupters, and more particularly to circuit interrupter operating mechanisms.  
           [0003]    Circuit interrupter operating mechanisms are used to manually control the opening and closing of movable contact structures within circuit interrupters. Additionally, these operating mechanisms in response to a trip signal, for example, from an actuator device, will rapidly open the movable contact structure and interrupt the circuit. To transfer the forces (e.g., to manually control the contact structure or to rapidly trip the structure with an actuator), operating mechanisms employ powerful springs and linkage arrangements. The spring energy provides a high output force to the separable contacts.  
           [0004]    Commonly, multiple contacts, each disposed within a cassette, are arranged within a circuit breaker system for protection of individual phases of current. The operating mechanism is positioned over one of the cassettes and generally connected to all of the cassettes in the system. Because of the close position between each of the cassettes, and between each cassette and the operating mechanism, the space available for movable components is minimal. It would be desirable to maximize the available space to reduce friction between movable components within the operating mechanism.  
           [0005]    Furthermore, circuit breaker arrangements are provided for 3-pole and 4-pole devices. Inherently, the position of a circuit breaker operating mechanism relative to a 4-pole device is asymmetrical. Therefore, it will be desirable to provide a circuit breaker operating mechanism that maximizes the output force to the poles of the circuit breaker system while minimizing the lost forces due to, for example, friction.  
         SUMMARY OF INVENTION  
         [0006]    An operating mechanism for controlling and tripping a separable contact structure arranged in a protected circuit is provided by the present invention. The separable contact structure is movable between a first and second position. The first position permits current to flow through the protected circuit and the second position prohibits current from flowing through the circuit. The mechanism includes a frame, a drive member pivotally coupled to the frame, a spring pivotally connecting the drive member to a drive connector, an upper link pivotally seated on the drive connector, a lower link member pivotally coupled to the drive connector, a crank member pivotally coupled to the lower link member for interfacing the separable contact structure, and a cradle member pivotally secured to the frame and pivotally securing the upper link.  
           [0007]    The cradle member is configured for being releasably engaged by a latch assembly, which is displaced upon occurrence of a predetermined condition in the circuit. The mechanism is movable between a tripped position, a reset position, an off position, and an on position.  
           [0008]    In one exemplary embodiment, spacers are operatively positioned between movable members, and protrusions are operatively formed on the enclosure. The spacers and protrusions serve to widen the stances of the operating mechanism for force distribution purposes, and also to minimize friction between movable components. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]    [0009]FIG. 1 is an isometric view of a molded case circuit breaker employing an operating mechanism embodied by the present invention;  
         [0010]    [0010]FIG. 2 is an exploded view of the circuit breaker of FIG. 1;  
         [0011]    [0011]FIG. 3 is a partial sectional view of a rotary contact structure and operating mechanism embodied by the present invention in the “off” position;  
         [0012]    [0012]FIG. 4 is a partial sectional view of the rotary contact structure and operating mechanism of FIG. 3 in the “on” position;  
         [0013]    [0013]FIG. 5 is a partial sectional view of the rotary contact structure and operating mechanism of FIGS. 3 and 4 in the “tripped” position;  
         [0014]    [0014]FIG. 6 is an isometric view of the operating mechanism;  
         [0015]    [0015]FIG. 7 is a partially exploded view of the operating mechanism;  
         [0016]    [0016]FIG. 8 is another partially exploded view of the operating mechanism;  
         [0017]    [0017]FIG. 9 is an exploded view of a pair of mechanism springs and associated linkage components within the operating mechanism;  
         [0018]    [0018]FIG. 10 is an isometric and exploded view of linkage components within the operating mechanism;  
         [0019]    [0019]FIG. 11 is a front, isometric, and partially exploded isometric views of a linkage component within the operating mechanism;  
         [0020]    [0020]FIG. 12 is a front, isometric, and partially exploded isometric views of linkage components within the operating mechanism;  
         [0021]    FIGS.  13  depicts isometric views of the opposing sides of a cassette employed within the circuit interrupter;  
         [0022]    [0022]FIG. 14 is a front view of the cassette and the operating mechanism positioned thereon; and  
         [0023]    [0023]FIG. 15 is a partial front view of the cassette and the operating mechanism positioned thereon. 
     
    
     DETAILED DESCRIPTION  
       [0024]    In an exemplary embodiment of the present invention, and referring to FIGS. 1 and 2, a circuit breaker  20  is shown. Circuit breaker  20  generally includes a molded case having a top cover  22  attached to a mid cover  24  coupled to a base  26 . An opening  28 , formed generally centrally within top cover  22 , is positioned to mate with a corresponding mid cover opening  30 , which is accordingly aligned with opening  28  when mid cover  24  and top cover  22  are coupled to one another.  
         [0025]    In a 3-pole system (i.e., corresponding with three phases of current), three rotary cassettes  32 ,  34  and  36  are disposed within base  26 . Cassettes  32 ,  34  and  36  are commonly operated by an interface between an operating mechanism  38  via a cross pin  40 . Operating mechanism  38  is positioned and configured atop cassette  34 , which is generally disposed intermediate to cassettes  32  and  36 . Operating mechanism  38  operates substantially as described herein and as described in U.S. patent application Ser. No. 09/196,706 entitled “Circuit Breaker Mechanism for a Rotary Contact Assembly”.  
         [0026]    A toggle handle  44  extends through openings  28  and  30  and allows for external operation of cassettes  32 ,  34  and  36 . Examples of rotary contact structures that may be operated by operating mechanism  38  are described in more detail in U.S. patent application Ser. Nos. 09/087,038 and 09/384,908, both entitled “Rotary Contact Assembly For High-Ampere Rated Circuit Breakers”, and U.S. patent application Ser. No. 09/384,495, entitled “Supplemental Trip Unit For Rotary Circuit Interrupters”. Cassettes  32 ,  34 ,  36  are typically formed of high strength plastic material and each include opposing sidewalls  46 ,  48 . Sidewalls  46 ,  48  have an arcuate slot  52  positioned and configured to receive and allow the motion of cross pin  40  by action of operating mechanism  38 .  
         [0027]    Referring now to FIGS. 3, 4, and  5 , an exemplary rotary contact assembly  56  that is disposed within each cassette  32 ,  34 ,  36  is shown in the “off”, “on” and “tripped” conditions, respectively. Also depicted are partial side views of operating mechanism  38 , the components of which are described in greater detail further herein. Rotary contact assembly  56  includes a line side contact strap  58  and load side contact strap  62  for connection with a power source and a protected circuit (not shown), respectively. Line side contact strap  58  includes a stationary contact  64  and load side contact strap  62  includes a stationary contact  66 . Rotary contact assembly  56  further includes a movable contact arm  68  having a set of contacts  72  and  74  that mate with stationary contacts  64  and  66 , respectively. In the “off” position (FIG. 3) of operating mechanism  38 , wherein toggle handle  44  is oriented to the left (e.g., via a manual or mechanical force), contacts  72  and  74  are separated from stationary contacts  64  and  66 , thereby preventing current from flowing through contact arm  68 .  
         [0028]    In the “on” position (FIG. 4) of operating mechanism  38 , wherein toggle handle  44  is oriented to the right as depicted in FIG. 3 (e.g., via a manual or mechanical force), contacts  72  and  74  are mated with stationary contacts  64  and  66 , thereby allowing current to flow through contact arm  68 . In the “tripped” position (FIG. 5) of operating mechanism  38 , toggle handle  44  is oriented between the “on” position and the “off” position (typically by the release of mechanism springs within operating mechanism  38 , described in greater detail herein). In this “tripped” position, contacts  72  and  74  are separated from stationary contacts  64  and  66  by the action of operating mechanism  38 , thereby preventing current from flowing through contact arm  68 . After operating mechanism  38  is in the “tripped” position, it must ultimately be returned to the “on” position for operation. This is effectuated by applying a reset force to move toggle handle  44  to a “reset” condition, which is beyond the “off” position (i.e., further to the left of the “off” position in FIG. 3), and then back to the “on” position. This reset force must be high enough to overcome the mechanism springs, described herein.  
         [0029]    Contact arm  68  is mounted on a rotor structure  76  that houses one or more sets of contact springs (not shown). Contact arm  68  and rotor structure  76  pivot about a common center  78 . Cross pin  40  interfaces through an opening  82  within rotor structure  76  generally to cause contact arm  68  to be moved from the “on”, “off” and “tripped” position.  
         [0030]    Referring now to FIGS.  6 - 8 , the components of operating mechanism  38  will now be detailed. As viewed in FIGS.  6 - 8 , operating mechanism  38  is in the “tripped” position. Operating mechanism  38  has operating mechanism side frames  86  configured and positioned to straddle sidewalls  46 ,  48  of cassette  34  (FIG. 2).  
         [0031]    Toggle handle  44  (FIG. 2) is rigidly interconnected with a drive member or handle yoke  88 . Handle yoke  88  includes opposing side portions  89 . Each side portion  89  includes an extension  91  at to the top of side portion  89 , and a U-shaped portion  92  at the bottom portion of each side portion  89 . U-shaped portions  92  are rotatably positioned on a pair of bearing portions  94  protruding outwardly from side frames  86 . Bearing portions  94  are configured to retain handle yoke  88 , for example, with a securement washer. Handle yoke  88  further includes a roller pin  114  extending between extensions  91 .  
         [0032]    Handle yoke  88  is connected to a set of powerful mechanism springs  96  by a spring anchor  98 , which is generally supported within a pair of openings  102  in handle yoke  88  and arranged through a complementary set of openings  104  on the top portion of mechanism springs  96 .  
         [0033]    Referring to FIG. 9, the bottom portion of mechanism springs  96  include a pair of openings  206 . A drive connector  201  operative couples mechanism springs  96  to other operating mechanism components. Drive connector  201  comprises a pin  202  disposed through openings  206 , a set of side tubes  203  arranged on pin  202  adjacent to the outside surface of the bottom portion of mechanism springs  96 , and a central tube  204  arranged on pin  202  between the inside surfaces of the bottom portions of mechanism springs  96 . Central tube  204  includes step portions at each end, generally configured to maintain a suitable distance between mechanism springs  96 . While drive connector  201  is detailed herein as tubes  203 ,  204  and a pin  202 , any means to connect the springs to the mechanism components are contemplated.  
         [0034]    Referring to FIGS. 8 and 10, a pair of cradles  106  are disposed adjacent to side frames  86  and pivot on a pin  108  disposed through an opening  112  approximately at the end of each cradle  106 . Each cradle  106  includes an edge surface  107 , an arm  122  depending downwardly, and a cradle latch surface  164  above arm  122 . Edge surface  107  is positioned generally at the portion of cradle  106  in the range of contact with roller pin  114 . The movement of each cradle  106  is guided by a rivet  116  disposed through an arcuate slot  118  within each side frame  86 . Rivets  116  are disposed within an opening  117  on each the cradle  106 . An arcuate slot  168  is positioned intermediate to opening  112  and opening  117  on each cradle  106 . An opening  172  is positioned above slot  168 .  
         [0035]    Referring back to FIGS.  6 - 8 , a primary latch  126  is positioned within side frame  86 . Primary latch  126  includes a pair of side portions  128 . Each side portion  128  includes a bent leg  124  at the lower portion thereof. Side portions  128  are interconnected by a central portion  132 . A set of extensions  166  depend outwardly from central portion  132  positioned to align with cradle latch surfaces  164 .  
         [0036]    Side portions  128  each include an opening  134  positioned so that primary latch  126  is rotatably disposed on a pin  136 . Pin  136  is secured to each side frame  86 . A set of upper side portions  156  are defined at the top end of side portions  128 . Each upper side portion  156  has a primary latch surface  158 .  
         [0037]    A secondary latch  138  is pivotally straddled over side frames  86 . Secondary latch  138  includes a set of pins  142  disposed in a complementary pair of notches  144  on each side frame  86 . Secondary latch  138  includes a pair of secondary latch trip tabs  146  that extend perpendicularly from operating mechanism  38  as to allow an interface with, for example, an actuator (not shown), to release the engagement between primary latch  126  and secondary latch  138  hereby causing operating mechanism  38  to move to the “tripped” position (e.g., as in FIG. 5), described below.  
         [0038]    Secondary latch  138  includes a set of latch surfaces  162 , that align with primary latch surfaces  158 .  
         [0039]    Secondary latch  138  is biased in the clockwise direction due to the pulling forces of a spring  148 . Spring  148  has a first end connected at an opening  152  upon secondary latch  138 , and a second end connected at a frame cross pin  154  disposed between frames  86 .  
         [0040]    Referring to FIGS. 8 and 10, a set of upper links  174  are connected to cradles  106 . Upper links  174  generally have a right angle shape. Legs  175  (in a substantially horizontal configuration and FIGS. 8 and 10) of upper links  174  each have a cam portion  171  that interfaces a roller  173  disposed between frames  86 . Legs  176  (in a substantially vertical configuration in FIGS. 8 and 10) of upper links  174  each have a pair of openings  182 ,  184  and a U-shaped portion  186  at the bottom end thereof. Opening  184  is intermediate to opening  182  and U-shaped portion  186 . Upper links  174  connect to cradle  106  via a securement structure such as a rivet pin  188  disposed through opening  172  and opening  182 , and a securement structure such as a rivet pin  191  disposed through slot  168  and opening  184 . Rivet pins  188 ,  191  both attach to a connector  193  to secure each upper link  174  to each cradle  106 . Each pin  188 ,  191  includes raised portions  189 ,  192 , respectively. Raised portions  189 ,  192  are provided to maintain a space between each upper link  174  and each cradle  106 . The space serves to reduce or eliminate friction between upper link  174  and cradle  106  during any operating mechanism motion, and also to spread force loading between cradles  106  and upper links  174 .  
         [0041]    Upper links  174  are each interconnected with a lower link  194 . Referring now to FIGS. 8, 10 and  11 , U-shaped portion  186  of each upper link  174  is disposed in a complementary set of bearing washers  196 . Bearing washers  196  are arranged on each side tube  203  between a first step portion  200  of side tube  203  and an opening  198  at one end of lower link  194 . Bearing washers  196  are configured to include side walls  197  spaced apart sufficiently so that U-shaped portions  186  of upper links  174  fit in bearing washer  196 . Each side tube  203  is configured to have a second step portion  201 . Each second step portion  201  is disposed through openings  198 . Pin  202  is disposed through side tubes  203  and central tube  204 . Pin  202  interfaces upper links  174  and lower links  194  via side tubes  203 . Therefore, each side tube  203  is a common interface point for upper link  174  (as pivotally seated within side walls  197  of bearing washer  196 ), lower link  194  and mechanism springs  96 .  
         [0042]    Referring to FIG. 12, each lower link  194  is interconnected with a crank  208  via a pivotal rivet  210  disposed through an opening  199  in lower link  194  and an opening  209  in crank  208 . Each crank  208  pivots about a center  211 . Crank  208  has an opening  212  where cross pin  40  (FIG. 2) passes through into arcuate slot  52  of cassettes  32 ,  34  and  36  (FIG. 2) and a complementary set of arcuate slots  214  on each side frame  86  (FIG. 8).  
         [0043]    A spacer  234  is included on each pivotal rivet  210  between each lower link  194  and crank  208 . Spacers  234  spread the force loading from lower links  194  to cranks  208  over a wider base, and also reduces friction between lower links  194  and cranks  208 , thereby minimizing the likelihood of binding (e.g., when operating mechanism  38  is changed from the “off” position to the “on” position manually or mechanically, or when operating mechanism  38  is changed from the “on” position to the “tripped” position of the release of primary latch  126  and secondary latch  138 ).  
         [0044]    Referring to FIG. 13, views of both sidewalls  46  and  48  of cassette  34  are depicted. Sidewalls  46  and  48  include protrusions or bosses  224 ,  226  and  228  thereon. Bosses  224 ,  226  and  228  are attached to sidewalls  46 ,  48 , or can be molded features on sidewalls  46 ,  48 . Note that cassette  34  is depicted and certain features are described herein because operating mechanism  38  straddles cassette  34 , i.e., the central cassette, in circuit breaker  20 . It is contemplated that the features may be incorporated in cassettes in other positions, and with or without operating mechanism  38  included thereon, for example, if it is beneficial from a manufacturing standpoint to include the features on all cassettes.  
         [0045]    Referring now to FIG. 14, side frames  86  of operating mechanism  38  are positioned over sidewall  46 ,  48  of cassette  34 . Portions of the inside surfaces of side frames  86  contact bosses  224 ,  226  and  228 , creating a space  232  between each sidewall  46 ,  48  and each side frame  86 . Referring now also to FIG. 15, space  232  allows lower links  194  to properly transmit motion to cranks  208  without binding or hindrance due to frictional interference from sidewalls  46 ,  48  or side frames  86 .  
         [0046]    Additionally, the provision of bosses  224 ,  226  and  228  widens the base of operating mechanism  38 , allowing for force to be transmitted with increased stability. Accordingly, bosses  224 ,  226  and  228  should be dimensioned sufficiently large to allow clearance of links  194  without interfering with adjacent cassettes such as cassettes  32  and  36 .  
         [0047]    Referring back to FIGS.  3 - 5 , the movement of operating mechanism  38  relative to rotary contact assembly  56  will be detailed.  
         [0048]    Referring to FIG. 3, in the “off” position toggle handle  44  is rotated to the left and mechanism springs  96 , lower link  194  and crank  208  are positioned to maintain contact arm  68  so that movable contacts  72 ,  74  remain separated from stationary contacts  64 ,  66 . Operating mechanism  38  becomes set in the “off” position after a reReferring back to FIGS.  3 - 5 , the movement of operating mechanism  38  relative to rotary contact assembly  56  will be detailed.set force properly aligns primary latch  126 , secondary latch  138  and cradle  106  (e.g., after operating mechanism  38  has been tripped) and is released. Thus, when the reset force is released, extensions  166  of primary latch  126  rest upon cradle latch surfaces  164 , and primary latch surfaces  158  rest upon secondary latch surfaces  162 . Each upper link  174  and lower link  194  are bent with respect to each side tube  203 . The line of forces generated by mechanism springs  96  (i.e., between spring anchor  98  and pin  202 ) is to the left of bearing portion  94  (as oriented in FIGS.  3 - 5 ). Cam surface  171  of upper link  174  is out of contact with roller  173 .  
         [0049]    Referring now to FIG. 4, a manual closing force was applied to toggle handle  44  to move it from the “off” position (i.e., FIG. 3) to the “on” position (i.e., to the right as oriented in FIG. 4). While the closing force is applied, upper links  174  rotate within arcuate slots  168  of cradles  106  about pins  188 , and lower link  194  is driven to the right under bias of the mechanism spring  96 . Raised portions  189  and  192  (FIG. 10) maintain a suitable space between the surfaces of upper links  174  and cradles  106  to prevent friction therebetween, which would increase the required set operating mechanism  38  from “off” to “on”. Furthermore, side walls  197  of bearing washers  196  (FIG. 11) maintain the position of upper link  174  on side tube  203  and minimize likelihood of binding (e.g., so as to prevent upper link  174  from shifting into springs  96  or into lower link  194 ).  
         [0050]    To align vertical leg  176  and lower link  194 , the line of force generated by mechanism springs  96  is shifted to the right of bearing portion  94 , which causes rivet  210  coupling lower link  194  and crank  208  to be driven downwardly and to rotate crank  208  clockwise about center  211 . This, in turn, drives cross pin  40  to the upper end of arcuate slot  214 . Therefore, the forces transmitted through cross pin  40  to rotary contact assembly  56  via opening  82  drive movable contacts  72 ,  74  into stationary contacts  64 ,  66 . Each spacer  234  on pivotal rivet  210  (FIGS. 9 and 12) maintain the appropriate distance between lower links  194  and cranks  208  to prevent interference or friction therebetween or from side frames  86 .  
         [0051]    The interface between primary latch  126  and secondary latch  138  (i.e., between primary latch surface  158  and secondary latch surface  162 ), and between cradles  106  and primary latch  126  (i.e., between extensions  166  and cradle latch surfaces  164 ) is not affected when a force is applied to toggle handle  44  to change from the “off” position to the “on” position.  
         [0052]    Referring now to FIG. 5, in the “tripped” condition, secondary latch trip tab  146  has been displaced (e.g., by an actuator, not shown), and the interface between primary latch  126  and secondary latch  138  is released. Extensions  166  of primary latch  126  are disengaged from cradle latch surfaces  164 , and cradles  106  is rotated clockwise about pin  108  (i.e., motion guided by rivet  116  in arcuate slot  118 ). The movement of cradle  106  transmits a force via rivets  188 ,  191  to upper link  174  (having cam surface  171 ). After a short predetermined rotation, cam surface  171  of upper link  174  contacts roller  173 . The force resulting from the contact of cam surface  171  on roller  173  causes upper link  174  and lower link  194  to buckle and allows mechanism springs  96  to pull lower link  194  via pin  202 . In turn, lower link  194  transmits a force to crank  208  (i.e., via rivet  210 ), causing crank  208  to rotate counter clockwise about center  211  and drive cross pin  40  to the lower portion of arcuate slot  214 . The forces transmitted through cross pin  40  to rotary contact assembly  56  via opening  82  cause movable contacts  72 ,  74  to separate from stationary contacts  64 ,  66 .  
         [0053]    As described above with respect to the setting from “off” to “on”, raised portions  189  and  192  (FIG. 10) maintain a suitable space between the surfaces of upper links  174  and cradles  106  to prevent friction therebetween. Furthermore, side walls  197  of bearing washers  196  (FIG. 11) maintain the position of upper link  174  on side tube  203  and minimize likelihood of binding (e.g., so as to prevent upper link  174  from shifting into springs  96  or into lower link  194 ). Additionally, spacers  234  (FIGS. 9 and 12) maintain the appropriate distance between lower links  194  and cranks  208  to prevent interference or friction therebetween or from side frames  86 . By minimizing friction between the movable components (e.g., upper links  174  vis a vis cradles  106 , upper links  174  vis a vis lower links  194  and springs  96 , and lower links  194  and cranks  208  vis a vis each other and side framed  86 ), the time to transfer the forces via operating mechanism  38  decreases.  
         [0054]    Raised portions  189  and  192 , sidewalls  197  of bearing washers  196 , and spacers  234  are also suitable to widen the base of operating mechanism  38 . This is particularly useful, for example, in an asymmetrical system, where the operating mechanism is disposed on one cassette in a four-pole system.  
         [0055]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.