Patent Publication Number: US-6211758-B1

Title: Circuit breaker accessory gap control mechanism

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to circuit breaker accessories, and, more particularly to gap control mechanisms for circuit breaker accessories. 
     Circuit breakers commonly implement accessories to add various functionalities. These accessories may provide a mechanical force to an operating mechanism of a circuit breaker, for example, in response to a trip event that provides an electronic signal to interrupt the circuit (i.e., electronic trip actuators, shunt trip actuators, under voltage actuators, etc.). 
     Accessories typically include movable linkages and members that change position to perform a function upon occurrence of a trip event. For example, the accessory may include an actuating mechanism that acts on a link in response to a trip event, such as the overcurrent conditions detected from various circuitry. The link, when not acted upon, engages or holds a trip member against the bias of a spring. When the link is acted upon, it disengages or releases the trip member, whereby the bias of the spring acts on the trip member. The trip member then provides a mechanical force to a circuit interrupter. However, after use, the trip member must be reset to the original, ready to trip position. After resetting, it is desirable that the space between the actuating mechanism and the link is consistently maintained so the release of the trip member is properly effectuated. 
     Furthermore, it is desirable to provide an engagement that prevents the members from becoming disengaged from each other due to vibrations occurring under normal operating conditions (commonly referred to as “shock-out”). It is also important that the engagement be quickly and reliable releasable upon occurrence of a trip event so that the motion of the members, hence the force provided to the operating mechanism, is rapid and unhindered. 
     For the foregoing reasons, there exists a particular need for an arrangement between movable members that consistently provides the desired spacing between the members, securely maintains the engagement between the members, and allows for rapid disengagement of the members upon occurrence of an event, i.e., a trip event. 
     SUMMARY OF THE INVENTION 
     An accessory for use with a circuit breaker is provided herein. The accessory is employed within a circuit breaker that includes a separable contact structure and an operating mechanism for opening and closing the separable contact structure. The accessory has an electrical or actuating device with a movable component. The movable component interfaces with a first member, or link, such that the first member is in a first position or latched position when the movable component is not actuated, and is moved to a second position or tripped position when the movable component is actuated. The first member also engages a second member, or trip member, when the first member is in the latched position. The second member is configured to interface the operating mechanism when the engagement between the first member and the second member is released, i.e., when the first member is moved to its second position. The second member includes a seat portion that interfaces the first member, whereby the shape and configuration of the seat portion sets a gap between the movable component and the first member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
     FIG. 1 is a top perspective view of a circuit breaker; 
     FIG. 2 is an exploded front perspective view of a circuit breaker; 
     FIG. 3 is a side perspective view of an accessory and an operating mechanism arranged within the circuit breaker of FIGS. 1 and 2; 
     FIG. 4 is an exploded front perspective view of an accessory employing embodiments of the present invention; 
     FIG. 5A is a side view of the accessory of FIG. 4 in the latched position; 
     FIG. 5B is an exploded view of a releasable engagement; 
     FIG. 6 is a side view of the accessory of FIG. 4 in the tripped position; 
     FIG. 7 is a side view of the accessory of FIG. 4 during resetting; 
     FIG. 8 is an enlarged side view of an embodiment of a releasable engagement employed within the accessory of FIGS. 3-7; 
     FIG. 9 is an enlarged side view of an alternative embodiment of a releasable engagement; and 
     FIG. 10 is an exploded front perspective view of an alternative accessory employing embodiments of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In an exemplary embodiment of the instant application, a circuit breaker  30  is shown in FIGS. 1 and 2. Circuit breaker  30  includes a base  32 , a mid cover  34  and an accessory cover  36  that assemble to enclose various circuit breaker components. Accessory cover  36  includes an operating handle  38  passing through an escutcheon  40 . Operating mechanism  42  allows for resetting of a series of cassettes  43  by the motion of operating handle  38  against the bias of mechanism springs. Operating mechanism  42  additionally receives mechanical action from an accessory  46 , which may be a device of the type including, but not limited to, electronic trip actuators, shunt trip actuators, under voltage actuators or bell alarms. Operating mechanism  42  is, for example, similar to that described in commonly owned and assigned U.S. application Ser. No. 09/196,706 (GE Docket Number 41PR-7540), entitled “Circuit Breaker Mechanism For A Rotary Contact System”, and in U.S. application Ser. No. 09/xxx,xxx (GE Docket Number 41PR-7566), entitled “Circuit Breaker Handle Block”. 
     Accessory  46  is positioned generally within mid cover  34  and is covered by accessory cover  36 . In one exemplary embodiment, accessory  46  is coupled to a trip unit  44  via a set of wires  45  to receive an electronic signal causing mechanical action within accessory  46 . 
     Cassettes  43  are, for example, of the rotary type and are positioned within base  32  and covered by mid cover  34 . Each of cassettes  43  typically includes a set of contacts therein that remain closed by forces of powerful contact springs thereby allowing current to pass through (i.e., quiescent operation). The contacts open upon an overcurrent condition that generate magnetic forces that are strong enough to overcome the forces of the contact springs (i.e., “blow-open forces”), or, in response to a trip signal provided to operating mechanism  42  by accessory  46 . The operation of cassettes  43  is described in more detail in, for example, in U.S. patent application Ser. Nos. 09/087,038 (GE Docket Number 41PR-7500) and 09/384,908 (GE Docket Number 41PR7613/7619), 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”. 
     Operating mechanism  42  is configured and positioned to interface with crossbars  48 , 49 . Crossbars  48 , 49  interact with cassettes  43  and are configured to maintain the contacts of all cassettes  43  in a common position (i.e., open or closed) under control of operating mechanism  42 . It is contemplated that the arrangement of cassettes  43  and operating mechanism  42  can vary depending on factors including, but not limited to, the number of phases of current, the type of circuit being protected, etc. 
     Referring now to FIG. 3, operating mechanism  42  and accessory  46  are depicted. Operating mechanism  42  generally includes, among other things, operating handle  38 , a handle-yoke  50 , a latch  52  and additional linkage to allow interaction between operating mechanism  42  and cassettes  43  via crossbars  48 , 49 . 
     Operating mechanism  42  includes various linkage and mechanism springs to move the contacts within cassettes  43  in the desired position. The movement may be effectuated externally (i.e., by manually or mechanically urging operating handle  38 ). Furthermore, the movement may be triggered by accessory  46 . When accessory  46  is actuated, a slide tab  54  will be displaced and transmit motion to a trip tab  56  of latch  52  (described further herein). Latch  52  is releasably coupled with another latch within operating mechanism  42  (not shown) against forces of one or more mechanism springs (not shown). When trip tab  56  is contacted by slide tab  54 , latch  52  decouples from the other latch (not shown) within operating mechanism  42 , thereby causing linkage to rotate crossbars  48 , 49  and open the contacts within cassettes  43 . 
     To reset operating mechanism  42 , handle  38  is urged (generally in the direction toward latch  52 ) until the mechanism springs of operating mechanism  42  are charged, i.e., ready to trip, and latch  52  is coupled within operating mechanism  42  to another latch (not shown). Handle-yoke  50  is interconnected with operating handle  38  and includes a reset tab  58  depending perpendicularly therefrom to allow interface with head  62  of a reset pin  60 . Reset pin  60  is disposed within accessory  46 , therefore, when operating mechanism  42  is reset by urging operating handle  38  (generally in the forward direction as shown in FIG.  3 ), reset tab  58  will accordingly transmit motion to head  62  and also reset accessory  46 . 
     Turning now to FIGS. 3-7, various views of accessory  46  are provided. It is, of course, contemplated that the accessory described with reference to FIGS. 3-7 is provided as an exemplary embodiment only. Therefore, the releasable engagement embodied by the present invention may be employed in, for example, other types of accessories or in other mechanisms where the configuration requires one member being releasably engaged from another member and particularly where a space is to be maintained between members. 
     Accessory  46  comprises a frame  64  having an electrical device such as an actuator  66 , a reset drive  70 , a slide  74 , and linkage including a plunger link  78  and a slide link  82 . A pivot pin  86  is positioned through opening  79  in plunger link  78 , openings  83  in slide link  82  and openings  71  in reset drive  70 . Pivot pin  86  is a common rotation center for reset drive  70 , plunger link  78 , and slide link  82 . Furthermore, reset drive  70  interfaces with plunger link  78  via a plunger reset spring  90 , and reset drive  70  interfaces with slide link  82  via a slide reset spring  94 . Plunger reset spring  90  and slide reset spring  94  are generally of the torsional type and are rotatably arranged on pivot pin  86  along with plunger link  78 , slide link  82  and reset drive  70 . A releasable engagement  122 , described in further detail herein, is generally effectuated between plunger link  78  and slide  74 . 
     Frame  64  includes sidewalls  98 , a spacer pin  102  and a back wall  106 . A trip member, configured as slide  74 , includes slide tab  54  for providing a trip action to operating mechanism  42  (at trip tab  56 ). Slide  74  is slideably maintained by a pair of slide rivets  110  that are disposed within slots  114  upon one sidewall  98 . A spring  118  is disposed around a portion of slide  74  having a first end that provides a force to slide  74  and a second end maintained against back wall  106 . During quiescent operation, slide  74  is maintained against the bias of spring  118 . It is, of course, contemplated that variations on the shape and configuration of slide  74  are possible depending on factors including but not limited to the shape of frame  64 , the space available in the circuit breaker case, the arrangement of the operating mechanism latches, etc. Additionally, the force provided may be from a spring that pulls slide  74 , rather than pushes slide  74  as shown with reference to the Figures herein. Furthermore, a second slide  74  may be arranged on the other sidewall  98 . These variations and alternative arrangements for slide  74  and the force provided to slide  74  will be apparent to one skilled in the art. 
     Referring particularly now to FIGS. 5A an  5 B, engagement  122  (shown in FIG. 5B by a partial enlarged view) is effectuated between a portion of slide  74  referred to as a seat  126  and a pin  130  depending from plunger link  78 . Pin  130  is generally cylindrical in cross-sectional shape and protrudes from plunger link  78  a distance sufficient to engage seat  126  as described herein. Various arrangements of engagement  122 , including the shape of seat  126 , will be detailed further herein. 
     Actuator  66  includes a movable member, such as a plunger  134 , that extends from actuator  66  in response to a signal provided upon the occurrence of a trip event or outside command through wires  45 . Actuator  66  is any suitable type, including, but not limited to magnetic actuators, spring-biased actuators or other mechanical actuator that responds to an electrical signal (i.e., through wires  45 ). Plunger  134  moves from a retracted or unextended (“loaded”) position during quiescent operation to a protruded or extended (“tripped”) position in response to a trip event. 
     Plunger link  78  is positioned and configured upon pivot pin  86  such that a gap  138  exists between plunger link  78  and plunger  134  during quiescent operation. The selected configuration of engagement  122  determines the size of gap  138 . When plunger  134  is moved to the protruded position, plunger link  78  is contacted. The contact causes plunger link  78  to rotate about pivot pin  86  (in the counter clockwise direction as oriented in the Figures) from a first position corresponding with quiescent operation (FIG.  5 A), whereby pin  130  is latched with respect to seat  126  of slide  74 , to a second position (FIG.  6 ), whereby pin  130  is released from seat  126 . 
     The release of engagement  122  allows spring  118  to extend and push slide  74 . Slide  74  traverses generally to the left from the latched position in FIG. 5 to the trip position as viewed in FIG.  6 . Slide  74  is generally guided by slide rivets  110  within slots  114  and traverses. Referring to FIGS. 3,  5 A, and  6 , this will cause slide tab  54  to contact trip tab  56 , and slide  74  traverses until spacer pin  102  stops the movement of slide  74 . 
     The rotation of plunger link  78  about pivot pin  86  in turn translates rotational motion to reset drive  70  via plunger reset spring  90 . Reset drive  70  includes reset pin  60  having head  62  arranged through openings  72  generally positioned upon the sides of reset drive  70 . Reset pin  60  is also disposed within C-shaped portions  84  of slide link  82 . Furthermore, reset pin  60  is disposed against surface  80  of plunger link  78 . Therefore, upon rotation of plunger link  78  due to contact from plunger  134 , reset drive  70  will rotate and accordingly carry reset pin  60 , causing plunger link  78  and slide link  82  to rotate about pivot pin  86 . 
     Referring to now to FIGS. 3,  4 , and  7 , the resetting of accessory  46  (and accordingly the reestablishment of engagement  122 ) will be described. Accessory  46  is reset when operating mechanism  42  is reset by the rotation of operating handle  38 . Upon rotation of operating handle  38  to reset the system (i.e., operating mechanism  42 , cassettes  43 , accessory  46 , etc.), reset tab  58  drives head  62  of reset pin  60 . The motion of reset tab  58  translates through reset pin  60  to reset drive  70 . Reset drive  70  rotates in the clockwise direction about pivot pin  86  and will accordingly transmit motion through slide reset spring  94  and plunger reset spring  90 . The motion transmitted to slide reset spring  94  will drive slide link  82  in the clockwise direction about pivot pin  86 , thereby urging the outside of C-shaped portion  84  against a rivet  76  arranged on slide  74 . Slide  74  is displaced against spring  118 . Additionally, the motion transmitted through plunger reset spring  90  will drive plunger link  78  in the clockwise direction about pivot pin  86 , thereby driving plunger  134  into the retracted position. The rotation of plunger link  78  also causes pin  130  to align with seat  126 . Therefore, when the reset force applied to operating handle  38  is removed, the system (i.e., accessory  46  and operating mechanism  42 ) is reset and engagement  122  is reestablished by the force of spring  118  driving slide  74  against pin  130 . 
     Accessory  46  as described thus far includes the interface at plunger reset spring  90  between reset drive  70  and plunger link  78 , and the interface at slide reset spring  94  between reset drive  70  and slide link  82 . These interfaces add absorbency when reset motion is applied. Accessory  46  including these spring interfaces as outlined above is similar to the device described in a copending and commonly assigned application U.S. Ser. No. 09/467,209, General Electric Docket Number 41PR-7648, entitled “Circuit Breaker Accessory Reset System”. It is contemplated that such an accessory is only one example of an accessory wherein engagement  122  and its variations described herein may be employed. 
     The shape and location of seat  126  determines the size of gap  138  between plunger  134  and plunger link  78 . Additionally, the shape and position may provide resistance to inadvertent disengagement of seat  126  and pin  130 . FIGS. 8 and 9 detail certain exemplary shapes of seat  126 . 
     FIG. 8 is an enlarged view of slide  74  showing an exemplary configuration of engagement  122  and seat  126 . 
     A consistently sized gap  138  is provided by engagement  122  including pin  130  holding slide  74  at seat  126 . Seat  126  comprises a corner  160  defined at the juncture of a first surface  162  and a second surface  164 . First surface  162  is generally a straight surface having a relatively shallow downward slope from left to right, and second surface  164  is an arcuate convex surface. In the latched condition, pin  130  is seated within corner  160  whereby pin  130  is in contact with first surface  162  and second surface  164 . 
     The selected position of corner  160  influences the set or latched position for slide  74  and plunger link  78 . For example, if first surface  162  were situated lower than is shown, or if the slope of first surface  162  were decreased (i.e., closer to horizontal), corner  160  would also be lower and the force of spring  118  would cause slide  74  to be positioned further to the left, and pin  130  would be seated further counter clockwise about pivot pin  86 . This would cause gap  138  between plunger link  78  and plunger  134  in the retracted position to increase. Conversely, if first surface  162  were situated higher than is shown, or if the slope of first surface  162  were greater (i.e., closer to vertical), corner  160  would also be higher and pin  130  would be seated further clockwise than is shown, therefore decreasing gap  138 . Additionally, the configuration and position of second surface  164  may be modified to change the size of gap  138 . It is, of course, contemplated that the configurations and positions of first surface  162 , second surface  164 , or both first surface  162  and second surface  164  may be modified to vary gap  138  or to provide or attenuate other benefits as described below. 
     The required size of gap  138  can vary depending on the particular usage. Gap  138  may be increased or decreased based on reasons including, but not limited to, the quantity of force generated by plunger  134 , the force required to decouple engagement  122 , the frictional resistance at the interface of pin  130  and seat  126 , and various system tolerances. 
     Other benefits are derived from the shape of seat  126  as provided in the embodiment of FIG.  8 . This position resists shock-out or premature disengagement. In order for pin  130  to become disengaged from seat  126  (i.e., upon counter clockwise rotation of plunger link  78  about pivot  86 ), the distance of second surface  164  must be cleared before the bias of spring  118  can push pin  130  back into corner  160 . The arcuate shape of second surface  164  requires a certain amount of force (i.e., from plunger  134 ) to move pin  130  past the apex of second surface  164 . Furthermore, the downward slope of first surface  162  provides leeway in the event of an inadvertent clockwise rotation of plunger link  78  so that pin  130  does not “bounce” off of a rigid surface and cause plunger link  78  to rotate counter clockwise. 
     Once the apex is reached, pin  130  will tend to accelerate when plunger link  78  is rotated about pivot pin  86  in response to a strike from protruding plunger  134 . This allows for a quick and smooth release when so desired. In an exemplary embodiment, the shape of arcuate second surface  164  is an arc having a radius at a center point  87  of pivot pin  86  (as indicated by dashed lines). In this configuration, the force required to release engagement  122  is primarily to overcome the friction between pin  130  and seat  126 . 
     Referring now to FIG. 9, an alternate configuration for engagement  122  is provided. Seat  126  is defined by the inside of a single arcuate surface  170 . Surface  170  is generally a concave arc configured to meet the required gap size. Furthermore, surface  170  may be configured to provide shock-out resistance. In this embodiment, the latched position, and hence gap  138 , is determined by the geometry of arcuate surface  170 , which dictates the position on surface  170  where pin  130  rests while slide  74  is pushed by spring  118 . 
     Engagement  122  as detailed herein provides a variety of features and combination of features. These features include, but are not limited to, setting the size of gap  138 , ensuring a rapid release between the first member (i.e., plunger link  78 ) and the second member or trip member (i.e., slide  74 ), and providing a reliable engagement between the first member in the second member that is resistant to, for example, external vibrations. These features may be varied by, for example, varying the configuration of the surface or surfaces. For example, surface  170  (FIG. 9) may be provided with a different radius. Alternatively, first and second surfaces  162  and  164  respectively (FIG. 8) may be provided with different sizes, shapes, and angles. For example, second surface  164  may be provided straight rather than arcuate. Furthermore, more than two surfaces may be provided to set gap  138 , where pin  130  will rest within a pocket created by a plurality of surfaces. 
     It is contemplated that alternative accessory arrangements, i.e., other than that described above with reference to FIGS. 3-7, may utilize any of the various engagements  122  described above and claimed by the instant application. One such alternative accessory arrangement which may be employed within the circuit interrupter is provided in FIG.  10 . 
     An accessory  140  as depicted in FIG. 10 includes a similar frame  64  (having sidewalls  98 , spacer pin  102  and back wall  106 ), actuator  66  (having plunger  134 ) and slide  74  (having seat  126  and guided by slide rivets  110  within slots  114  of one sidewall  98 ). Accessory  140  further includes a monolithic reset drive  142  disposed on pivot pin  86  (at a set of openings  143 ), reset drive  142  including a reset tab interface  146 . Reset tab interface  146  receives motion from reset tab  58  of operating mechanism  42  in a similar manner as described above with reference to FIG. 3-7 (i.e., the motion transmitted from reset tab  58  to head  62  of reset pin  60 ). Additionally, reset tab interface transmits  146  reset motion directly to slide  74   
     A linkage member  150  is also arranged on pivot pin  86  (at an opening  151 ) and is configured to link the action of plunger  134  with slide  74 . Linkage member  150  is further configured to transmit reset motion from reset drive  142  to plunger  68  via a reset spring  154 . Reset spring  154  may be arranged separately from reset drive  142  and linkage member  150 , or reset spring  154  may be integral with either reset drive  142  (as shown in FIG. 18) or with linkage member  150  (not shown). 
     Linkage member  150  includes a pin  158  protruding therefrom for engaging slide  74  at seat  126  (i.e., engagement  122 ). In the latched position, engagement  122  maintains slide  74  against the force of spring  118 , as described above with reference to FIGS. 3-7. When plunger  134  is caused to protrude, it contacts linkage member  150  thereby releasing engagement  122  and allowing slide  74  to traverse. As described above, when slide  74  traverses, motion is transferred to trip tab  56  of latch  52 , thereby causing operating mechanism  42  to open the contacts of cassettes  43 . 
     Other arrangements of accessory  46  (or accessory  140 ) that may utilize engagement  122  will be apparent to one skilled in the art. For instance, the movement of the various members may have different directions, or be effectuated by alternative means. For example, a second member (i.e., slide  74 ) may have a different type of biasing member (i.e., other than spring  118 ). The biasing member may be, for example, a leaf spring or torsional spring. In yet another alternative means for providing motion to the second member, a spring may be used to pull the second member (rather than push the second member as described above with reference to FIGS.  3 - 7 ). 
     Additionally, the type of motion may vary. While the above examples have been described with reference to a first member (i.e., plunger link  78 ) having rotational motion (i.e., about pivot pin  86 ) and a second member (i.e. slide  74 ) having linear motion (i.e., guided by slide rivets  110  disposed through slots  114 ), alternative arrangements having different motion relationships between the first and second members are contemplated. 
     For example, the first member may be configured for linear motion, i.e., in angular or vertical direction away from the second member, the second member being configured for horizontal linear motion as described above. The first member may be configured, for instance, by providing an interior guiding frame that allows the first member to traverse. 
     In another alternative, the first member may be configured for linear motion and the second member may be configured for rotational motion. The first member may be configured as described above, or may be configured for horizontal linear motion. The second member may be configured to rotate about a pivot, wherein the frame is shaped accordingly to allow, for example, a component simliar to slide tab  54  to contact trip tab  56 . 
     While the invention has been described with reference to a preferred embodiment and various alternative embodiments, it will be understood by those skilled in the art that changes may be made and equivalents may be substituted for elements thereof without departing from the scope of 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.