Patent Publication Number: US-11657986-B2

Title: Damper and latching assemblies for electrical switching devices

Description:
BACKGROUND 
     This disclosure relates generally to electrical switching devices. More particularly, this disclosure describes a high-speed switching device having a damper and latching assembly. The assembly is configured to dampen the movement of a moving contact of the switching device as the moving contact translates from its closed position to its open position. The assembly also is configured to restrain the moving contact in its open position. The assembly stores at least some of the energy associated with the damping process, and uses the stored energy to assist in the release of the moving contact during the subsequent re-closing of the switching device. 
     High-speed switching devices typically include one or more moving contacts that translate into and out of contact with an associated stationary contact, to selectively establish and disestablish a path for conducting electric current. The moving contact typically is mounted on a linearly-translating switch shaft. Under routine operating conditions, the moving contact is biased against the stationary contact so that current is transmitted through the switching device by way of the moving and stationary contacts. The bias may be provided by one or more linear springs, toggling washers, or other means. 
     It may become necessary to rapidly switch the current path during non-routine operating conditions. For example, during an overcurrent condition, the moving and stationary contacts need to be rapidly separated so that the fault current can be shunted to other electrical devices configured to interrupt, reduce, or otherwise handle the fault current. To achieve such rapid separation, the switch may be equipped with a high-speed coil, such as a Thomson coil, that causes the switch shaft, and the attached moving contact, to translate away from the stationary contact at a very high rate of speed. The switching device also may include a low-speed coil for opening the contacts under routine operating conditions, by causing the switch shaft and the moving contact to translate away from the stationary contact at a relatively low rate of speed. Once the moving contact reaches its open positon at the end of the fast or slow opening sequences, the moving contact is restrained in the open position, against the bias of the closing springs or the toggling washers, by some type of restraining means that engages the switch shaft. 
     The switch shaft may rebound upon reaching the end of its travel during the opening sequence. Such rebounding has the potential to cause the switch shaft to become free from its restraining means, which can result in the premature and unintentional return of the moving contact to its closed position. Rebounding also can result in premature wear of the switch shaft and other components. Due to the high rate of speed imparted to the moving contact by the high-speed solenoid, the switch may include a fast brake system that slows the switch shaft and the attached moving contact after the moving contact has separated from the stationary contact during the fast-opening sequence. The fast brake system operates during high-speed opening only, and reduces the potential for rebounding of the switch shaft. 
     Due to the operating characteristics of a typical secondary coil, the speed of the switch shaft and the moving contact may increase as the moving contact approaches its open position during the slow-opening sequence. Thus, the potential for rebounding of the switch shaft during the slow-opening sequence can be substantial. 
     Also, the force needed to latch or otherwise restrain the switch shaft and the moving contact against the bias of the closing springs or toggling washers can be substantial. Thus, the frictional or other forces that need to be overcome as the switch shaft is released during re-closing of the switch likewise can be substantial, and potentially can interfere with the re-closing of the switch. 
     SUMMARY 
     In one aspect, the disclosed technology relates to an electrical switching device that includes a sidewall, a first shaft configured to translate between a first and a second position in relation to the sidewall; a first contact mounted on the first shaft; and a second contact. The first contact and the first shaft are configured so that the first contact is in electrical contact with the second contact when the first shaft is in the first position, and the first contact is out of electrical contact with the second contact when the first shaft is in the second position. 
     The electrical switching device also includes a damper and latching assembly. The damper and latching assembly includes the first shaft; a second shaft mounted for rotation on the sidewall, the second shaft being configured so that, during operation, the first shaft rotates the second shaft from a first to a second angular position of the second shaft as the first shaft moves from the first to the second position of the first shaft; and a first rotating member mounted for rotation on the sidewall between a first and a second angular position. The first rotating member includes a third shaft. The third shaft is configured to, during operation, engage the first shaft when the first shaft is in the second position of the first shaft and the first rotating member is in the second angular position of the first rotating member. The engagement of the third shaft and the first shaft restraining the first shaft in the second position of the first shaft. 
     The damper and latching assembly also includes a spring coupled to the second shaft and configured so that, during operation, rotation of the second shaft from the first to the second angular position of the second shaft imparts energy to the spring, and at least a portion of the energy imparted to the spring biases the first rotating member toward the first angular position of the first rotating member as the first rotating member rotates from the second to the first angular position of the first rotating member. 
     In another aspect of the disclosed technology, the first shaft is biased toward the first position of the first shaft and is configured to, during operation, move from the second to the first position of the first shaft as the first rotating member rotates from the second to the first angular position of the first rotating member. 
     In another aspect of the disclosed technology, the damper and latching assembly further includes a second rotating member mounted on the second shaft and configured so that, during operation, rotation of the second shaft from the first to the second angular position of the second shaft causes the second rotating member to rotate from a first to a second angular position of the second rotating member; and a third rotating member mounted for rotation on the sidewall. The third rotating member is coupled to the second rotating member and the spring and is configured so that, during operation, rotation of the second rotating member from the first to the second angular position of the second rotating member causes the third rotating member to rotate from a first to a second angular position of the third rotating member, and the third rotating member imparts the energy to the spring as the third rotating member is rotated from the first to the second angular position of the third rotating member. 
     In another aspect of the disclosed technology, the first rotating member is configured so that, during operation, rotation of the third rotating member from the first to the second angular position of the third rotating member causes the first rotating member to rotate from the first to the second angular position of the first rotating member. 
     In another aspect of the disclosed technology, the spring is a first spring; the damper and latching assembly further includes a second spring coupled to the first rotating member and the sidewall; and the second spring is configured to, during operation, bias the first rotating member toward the second angular position of the first rotating member. 
     In another aspect of the disclosed technology, the spring is a torsion spring and is configured so that, during operation, the rotation of the third rotating member from the first to the second angular position of the third rotating member imparts the energy to the spring by winding the spring. 
     In another aspect of the disclosed technology, the energization of the spring dampens the movement of the first shaft from the first to the second position of the first shaft. 
     In another aspect of the disclosed technology, the third shaft has a substantially D-shaped cross section. 
     In another aspect of the disclosed technology, the damper and latching assembly further includes a coupling member, a mounting pin that engages the coupling member and the second rotating member, and a coupling pin that engages the coupling member and the third rotating member. The second rotating member is coupled to the third rotating member by way of the coupling member, the mounting pin, and the coupling pin. The coupling member is configured so that, during operation, the coupling pin is disengaged from the third rotating member when the second rotating member is in the second angular position of the second rotating member thereby decoupling the third rotating member from the second rotating member. 
     In another aspect of the disclosed technology, the third rotating member includes a side member having an opening formed therein; and the coupling pin is configured to, during operation, reside within the opening and out of contact with the third rotating member when the second rotating member is in the second angular position of the second rotating member. 
     In another aspect of the disclosed technology, the damper and latching assembly further includes a solenoid, and a paddle connected to the solenoid. The solenoid is configured to, during operation, rotate the paddle between a first and a second angular position of the paddle; and the paddle is configured to contact the third rotating member when the third rotating member is in the second angular position of the third rotating member, and to rotate the third rotating member toward the first angular position of the third rotating member as the paddle moves from the first to the second angular position of the paddle. 
     In another aspect of the disclosed technology, the spring is further configured to, during operation, bias the third rotating member toward the first angular position of the third rotating member as the third rotating member rotates from the second to the first angular position of the third rotating member. 
     In another aspect of the disclosed technology, the spring is further configured to bias the third rotating member toward the first position of the third rotating member using at least a portion of the energy imparted to the spring by the rotation of the second shaft from the first to the second angular position of the second shaft. 
     In another aspect of the disclosed technology, the spring is further configured to, during operation, bias the third rotating member toward the second position of the third rotating member when the third rotating member is in the second angular position of the third rotating member. 
     In another aspect of the disclosed technology, the third rotating member is configured so that, during operation, the third rotating member rotates the third shaft from the second to the first position of the third shaft as the third rotating member rotates from the second to the first position of the third rotating member, thereby releasing the first shaft from the third shaft. 
     In another aspect of the disclosed technology, the first shaft includes a step, and the third shaft is further configured to, during operation, engage the step when the first shaft is in the second position of the first shaft and the first rotating member is in the second angular position of the first rotating member; and the engagement of the step and the first shaft restrains the first shaft in the second position of the first shaft. 
     In another aspect of the disclosed technology, the spring is a first spring; the damper and latching assembly further includes a second spring coupled to the coupling member and the second rotating member; and the second spring is configured to, during operation, bias the coupling member in an orientation at which coupling pin remains disengaged from the third rotating member when the second rotating member is in the second angular position of the second rotating member. 
     In another aspect of the disclosed technology, the first shaft has a substantially planar surface; the second shaft has a substantially planar surface configured to, during operation, contact the surface of the first shaft as the first shaft rotates the second shaft from the first to the second angular position of the second shaft; and an orientation of the surface of the first shaft substantially matches an orientation of the surface of the second shaft as the first shaft rotates the second shaft from the first to the second angular position of the second shaft. 
     In another aspect of the disclosed technology, the first shaft is configured to, during operation, prevent rotation of the first rotating member from the first to the second position of the first rotating member when the first shaft is in the first position of the first shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side view of an electrical switch having a damper and latching assembly, with a sidewall of the switch removed for purposes of illustration, and showing the switch in a closed state. 
         FIG.  2    is a cross-sectional view of the electrical switch shown in  FIG.  1    without a case, taken through the line A-A of  FIG.  1   , showing the switch in the closed state, and depicting additional component of the switch. 
         FIG.  3    is a magnified side view of the area designated “B” in  FIG.  1   , depicting certain components of the switch in phantom. 
         FIG.  4    is a magnified rear-perspective side view of the area designated “B” in  FIG.  1   . 
         FIG.  5    is a partially exploded view of the electrical switch shown in  FIGS.  1 - 4   . 
         FIG.  6    is a view of the area depicted in  FIG.  3   , showing the damper and latching assembly when the switch in the closed state, and depicting additional components of the switch in phantom. 
         FIGS.  7 - 11    are views of the area depicted in  FIGS.  3  and  6   , showing the damper and latching assembly sequentially as the switch moves from the closed state and toward the open state. 
         FIG.  12    is a view of the area depicting in  FIGS.  3  and  6 - 11   , showing the damper and latching assembly when the switch in the open state. 
         FIGS.  13 - 15    are views of the area depicting in  FIGS.  3  and  6 - 12   , depicting the damper and latching assembly sequentially as the switch moves from the open state and toward the closed state. 
     
    
    
     DETAILED DESCRIPTION 
     As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. As used in this document, the term “comprising” (or “comprises”) means “including (or includes), but not limited to.” When used in this document, the term “exemplary” is intended to mean “by way of example” and is not intended to indicate that a particular exemplary item is preferred or required. 
     Other terms that are relevant to this disclosure will be defined at the end of this Detailed Description section. 
     The figures depict a damper and latching assembly  10  for a switching device such an electrical switch  200 . Referring initially to  FIGS.  1 ,  2 , and  5   , the switch  200  comprises a switching assembly  202  configured to form a current path between a first and a second terminal (not shown) of the switch  200 . The switching assembly  202  includes a first, or moving contact  204 ; and a second, or stationary contact  206 , visible in  FIG.  5   . The moving contact  204  is securely mounted on a first end of a shaft in the form of a switch shaft  34 ; and is configured to translate linearly, between a first, or closed position depicted in  FIG.  5   , and a second, or open position (not shown). The moving contact  204 , when in the closed position, is in physical and electrical contact with the stationary contact  206 , thereby facilitating the flow of electric current between the first and second terminals. When in the open position, the moving contact  204  is spaced apart, and electrically isolated from the stationary contact  206 ; thus, current does not flow thorough the switch  200  when the moving contact  204  is in the open position. 
     The switch  200  also comprises a closing spring assembly  207  that biases the moving contact  204  toward its closed position, and into contact with the stationary contact  206 . The closing spring assembly  207  can be, for example, a closing spring assembly as described in U.S. patent application Ser. No. 17/180,068, the contents of which are incorporated by reference herein in their entirety. Other means for biasing the moving contact  204  can be used in lieu of the closing spring assembly  207 . For example, the biasing force can be provided by one or more toggling Bellville washers in alternative embodiments. 
     The switch  200  also includes a drive  208  configured to actuate the switching assembly  202 . As can be seen in  FIG.  5   , the drive  208  includes a plunger  210 ; a high-speed or primary coil  212  located adjacent the plunger  210 ; and a low-speed or secondary coil  216 . The plunger  210  is securely connected to a second end of the switch shaft  34 . The primary coil  212  is used to open the switch  200  in a rapid, or fast-opening sequence. The secondary coil  216  is used to open in switch  200  in a slow-opening sequence. The primary coil  212  and the secondary coil  216  generate a varying magnetic flux when energized with a pulsating electric current during the respective fast and slow opening sequences. The magnetic flux induces an oppositely flowing electric current within the plunger  210 . The opposing currents generate a repulsive force between the primary coil  212  or the secondary coil  216 , and the plunger  210 . The repulsive force drives the plunger  210 , and the attached switch shaft  34 , away from the primary coil  212 . The primary coil  212  is a Thomson coil; other types of coils can be used in alternative embodiments. 
     The switch shaft  34  is configured to translate linearly between a first, or closing position and a second, or opening position. When in the closing position, the switch shaft  34  urges the moving contact  204  into its closed position against the stationary contact  206 . When in the opening position, the switch shaft  34  holds the moving contact  204  is its open position, spaced apart from the stationary contact  206 . 
     The switch shaft  34  resides in its closing position, depicted in  FIGS.  1 - 4  and  6   , when the primary coil  212  or the secondary coil  216  are not energized and the switch shaft  34  is not being restrained in its opening position by the damper and latching assembly  10 . The movement of plunger  210  in response to energization of the primary coil  212  causes the switch shaft  34  to translate linearly, to its opening position, which in turn causes the moving contact  204  to translate rapidly toward its open position. The moving contact  204  is opened by the primary coil  212  when it is necessary to rapidly separate the moving contact  204  from the stationary contact  206 , such as upon the detection of an overcurrent condition. For example, the primary coil  212  can be configured to cause the moving contact  204  to translate one millimeter in about 0.00025 seconds. 
     The switch  200  also includes a fast-brake system (not shown) that slows the switch shaft  34  and the moving contact  204  after the moving contact  204  has separated from the stationary contact  206  during the fast-opening sequence. The secondary coil  216  can be sized to the largest size possible that can be dampened reliably and not result in premature wear or parts damage, so that the damping force provided by the damper and latching assembly  10  also can be used to provide a slowing effect at the end of the fast opening sequence. Thus, the fast brake system can work less, which in turn can increase the reliability of the fast brake system. The secondary coil  216  can be sized in other manners in alternative embodiments. 
     The secondary coil  216  configured to move the switch shaft  34  to its opening position at a much slower rate than the primary coil  212 . The secondary coil  216  is used to move the moving contact  204  under routine circumstances that do not require the nearly instantaneous separation of the moving contact  204  and the stationary contact  206  provided by the primary coil  212 . The fast-brake system does not operate during the slow-opening sequence. 
     The switch  200  also includes two sidewalls  218  located on opposite sides of the switch  200 , as shown in  FIG.  1   . 
     The damper and latching assembly  10  is configured to dampen the movement of the moving contact  204  and the switch shaft  34  as the moving contact  204  translates from its closed position to its open position. The assembly  10  also is configured to restrain the moving contact  204  in its open position. The assembly  10  stores at least some of the energy associated with the damping process, and uses the stored energy to assist in the release of the moving contact  204  during the subsequent re-closing of the switch  200 . 
     Referring to  FIGS.  1  and  3 - 5   , the damper and latching assembly  10  comprises a first rotating member in the form of a d-shaft subassembly or latching subassembly  22 , a second rotating member in the form of a reset lever  20 ; a third rotating member in the form of a hammer  24 ; a first shaft in the form of the switch shaft  34 ; a second shaft in the form of a reset shaft  26 ; a hammer spring  28 ; a claw spring  27 ; a hammer claw or coupling member  30 , and a closing solenoid  35 . Directional references such as clockwise, counterclockwise, right, and left are used with reference to the component orientations depicted  FIGS.  1 - 3  and  6 - 15   . 
     Reset Lever  20   
     Referring to  FIGS.  3 - 5   , the second rotating member, or reset lever  20 , includes a first side member  40   a , and a substantially identical second side member  40   b . The first and second side members  40   a ,  40   b  are secured to each other, and are maintained in an opposing, spaced-apart relationship by a lower pin  42 , an upper pin  44 , and a balance weight  46 , each of which is secured to the first and second side members  40   a ,  40   b  by riveting or other suitable means. The balance weight  46  is located at the bottom of the reset lever  20 , and provides a counterbalancing effect that helps to prevent shock during fast opening of the switch  200  by the primary coil  212 . Each of the first and second side members  40   a ,  40   a  has an arcuate first slot  47 , and an arcuate second slot  48  formed therein as can be seen, for example, in  FIGS.  5  and  9   . 
     Reset Shaft  26   
     Referring again to  FIGS.  3 - 5   , the second shaft, or reset shaft  26 , includes two end portions  50 , and a center portion  51  disposed between the end portions  50 . The center portion  51  includes two flanges  53 , and a flat center member  54 . The center member  54  adjoins, and is disposed between the flanges  53 ; and has a substantially planar surface  130 . Each end portion  50  includes an inner member  55  having a substantially square cross-section; and an outer member  56  having a substantially circular cross section. Each inner member  55  extends through a substantially square hole formed a respective one of first and second side members  40   a ,  40   b  of the reset lever  20 . The inner members  55  are sized to fit within the square openings with minimal clearance, so that the reset shaft  26  and the reset lever  20  rotate together. 
     Each outer member  56  extends through a substantially circular hole formed in a respective one of the sidewalls  218 . The outer members  56  are sized to fit within the holes with minimal clearance, so that the resent shaft  26  and the attached reset lever  20  are suspended from, and can rotate in relation to the sidewalls  218 . 
     The reset shaft  26  is restrained from lateral movement in relation to the sidewalls  218 , i.e., movement in a direction coinciding with the axis of rotation of the reset shaft  26 , by e-clips  59  that engage grooves formed in the outer members  56 , as shown in  FIG.  4   . The reset shaft  26  can be restrained from lateral movement by other means in alternative embodiments. The reset lever  20  is restrained from lateral movement in relation to the reset shaft  26  by the flanges  53  of the reset shaft  26 . The reset lever  20  is biased in the clockwise direction by a torsion spring  60  positioned on one of the outer members  56 . 
     Hammer  24   
     Referring to  FIGS.  3 - 5   , the third rotating member, or hammer  24 , includes a first side member  62   a , and a substantially identical second side member  62   b . The first and second side members  62   a ,  62   b  are secured to each other, and are maintained in an opposing, spaced-apart relationship by a lower pin  63 , an intermediate pin  64 , and an upper pin  65 , each of which is secured to the first and second side member  62   a ,  62   b  by an interference fit or other suitable means. The hammer  24  also includes a cross-member  81 . The cross member  81  extends between the first and second side members  62   a ,  62   b  as can be seen in  FIG.  5   , and has a substantially square cross section. 
     Each side member  62   a ,  62   b  has an opening  66  formed therein. The opening  66  includes a recessed area, or detent  68 , as can be seen in  FIGS.  4  and  12   . Each of the side members  62   a ,  62   b  also has a notch  69  formed in a forward edge thereof, as can be seen in  FIG.  12   . 
     The hammer  24  is coupled to and suspended from the sidewalls  218  by a mounting pin  70 . The mounting pin  70  is received in holes formed in the first and second side member  62   a ,  62   b . The mounting pin  70  is sized to fit within the holes with minimal clearance, so that the hammer  24  can rotate on the mounting pin  70 . The mounting pin  70  has reduced-diameter end portions  71 , as can be seen in  FIG.  4   . Each end portion  71  extends through a hole formed in a respective one of the sidewalls  218 . The end portions  71  are sized to fit within the holes with minimal clearance, so that the mounting pin  70  can rotate in relation to the sidewalls  218 . 
     The hammer  24  is coupled to, and is biased for rotation toward the latching subassembly  22  by two extension springs  73  each connected to the cross member  81  of the hammer  24 , and to a respective one of the upper arms  104  of the latching subassembly  22 . The hammer  24  is balanced about its point of rotation to help prevent shock caused by the fast opening of the switch  200 . 
     Coupling Member  30   
     Referring to  FIGS.  3 - 6   , the hammer claw, or coupling member  30 , includes a first side member  74   a , a substantially identical second side member  74   b , and a mounting pin  75 . The mounting pin  75  extends between the first and second side members  74   a ,  74   b , and through holes formed in the respective first and second side members  74   a ,  74   b . The holes are sized that mounting pin  75  fits within the holes with minimal clearance, allowing the first and second side members  74   a ,  74   b  to rotate freely in relation to the mounting pin  75 . The respective ends of the mounting pin  75  are secured to the first and second side members  74   a ,  74   b  by welding or other suitable means. The coupling member  30  thus is suspended from, and can rotate in relation to the reset lever  20 . As can be seen in  FIG.  4   , the mounting pin  75  includes shoulders that help to restrain the first and second side members  74   a ,  74   b  from lateral movement, i.e., from movement in a direction coinciding with the longitudinal axis of the mounting pin  75 . 
     The coupling member  30  also includes a first pin  78 , a substantially identical second pin  80 , and a third pin or coupling pin  82 , each of which extends between the first and second side members  74   a ,  74   b . The respective ends of the first, second, and third pins  78 ,  80 ,  82  are positioned within holes formed in the first and second side members  74   a ,  74   b . The holes are sized so that the ends of the first, second, and third pins  78 ,  80 ,  82  fit within the holes with minimal clearance, allowing the first, second, and third pins  78 ,  80 ,  82  to rotate freely in relation to the first and second side member  74   a ,  74   b . The first, second, and third pins  78 ,  80 ,  82  have shoulders that restrain the first, second, and third pins  78 ,  80 ,  82  from lateral movement in relation to the first and second side members  74   a ,  74   b.    
     The ends of the first pin  78  extend outward from the respective first and second side members  74   a ,  74   b , and are disposed in the first slots  47  formed in the respective first and second side members  40   a ,  40   b  of the reset lever  20 , as can be seen in  FIG.  12   . The ends of the second pin  80  likewise extend outward from the respective first and second side members  74   a ,  74   b , and are disposed in the second slots  48  formed in the respective first and second side members  40   a ,  40   b . The ends of the third pin  82  extend outward from the respective first and second side members  74   a ,  74   b , and are disposed in the openings  66  formed in the respective first and second side members  62   a ,  62   b  of the hammer  24 , as can be seen in  FIG.  4   . 
     The claw spring  27  is an extension spring, and is attached to the first pin  78 , and the upper pin  44  of the reset lever  20 , as can be seen in  FIG.  4   . Other types of springs can be used as the claw spring  27  in alternative embodiments. 
     Hammer Spring  28   
     Referring to  FIGS.  3 - 5   , the hammer spring  28  is a torsion spring, and is mounted on a pin  84  that extends between the sidewalls  218 . The hammer spring  28  operates in conjunction with a cam  86 . The cam  86  comprises a sleeve  88 , and an arm  90  that adjoins the sleeve  88 . The sleeve  88  is positioned over, and can rotate in relation to the pin  84  as shown in  FIG.  3   . The arm  90  is configured to engage a grooved roller  92  mounted for rotation on the upper pin  65  of the hammer  24 . A first end of the hammer spring  28  engages a grooved stop  94  secured to one of the sidewalls  218  as shown in  FIG.  4   ; and a second end of the hammer spring  28  engages the arm  90  so that the hammer spring  28  biases the hammer  24  in a counterclockwise direction. 
     Latching Subassembly  22   
     Referring to  FIGS.  3 - 5   , the first rotating member, or latching subassembly  22 , comprises a third shaft in the form of a middle portion, or shaft  98 ; and two end portions  100 . The shaft  98  has a substantially D-shaped cross section. The shaft  98  can be seen in  FIG.  5   . The shaft  98  is depicted in phantom in  FIGS.  3  and  6 - 15   . Each end portion  100  comprises a hub  102  that adjoins a respective end of the shaft  98 . Each end portion  100  also includes an upper arm  104  and a lower arm  106  that adjoin the hub  102 . The upper arms  104  each have a lip  107  on an upper end thereof. 
     Each of the end portions  100  also includes a cylindrical projection  108  that adjoins an outward-facing side of the associated hub  102 , as can be seen in  FIG.  4   . Each projection  108  is received in a hole formed in a respective one of the sidewalls  218 . The projections  108  are sized to fit within the holes  112  with minimal clearance, so that the latching subassembly  22  is suspended from, and can rotate in relation to the sidewalls  218 . The latching subassembly  22  is configured to rotate between a first, or latching position shown in  FIGS.  11 - 15   , and a second, or releasing position shown in  FIGS.  3 , and  6 - 10   . 
     The latching subassembly  22  is restricted from lateral movement, i.e., movement in a direction coinciding with the axis of rotation of the latching subassembly  22 , by contact between the end portions  100  and the respective sidewalls  218 . 
     Switch Shaft  34   
     As can be seen in  FIG.  5   , the first shaft, or switch shaft  34 , has a forward portion  112 , an intermediate portion  114  that adjoins the forward portion  114 , and a rearward portion  116  that adjoins the intermediate portion  112 . The intermediate portion  114  has an upward-facing first planar surface  118 , and upward-facing second planar surface  119 , and a step or lip  120  that adjoins first and second planar surfaces  118 ,  119 . As can be seen in  FIG.  3   , the second planar surface  119  has a higher elevation than the first planar surface  118 . The rearward portion  116  has a substantially planar, rearward-facing surface  121 , as also can be seen in  FIG.  5   . 
     Closing Solenoid  35   
     As shown in  FIG.  3   , the closing solenoid  35  includes a solenoid  122 , and an arm or paddle  124  connected to the solenoid  122 . The solenoid  122  is configured to rotate the paddle  124  between a first, or opening position shown in  FIG.  3   , and a second, or closing position shown in  FIG.  15   . The paddle  124  is balanced about its point of rotation to help prevent shock caused by the fast opening of the switch  200 . 
     Operation of the Assembly  10  During Opening of the Switch  200   
     The assembly  10  latches the switch shaft  34  in its open position, against the force of the closing spring assembly  207 , by the engagement of the latching subassembly  22  and the switch shaft  34 . During opening of the switch  200 , the assembly  10  stores a portion of the energy imparted to the switch shaft  34  by the secondary coil  216 . This energy storage dampens the movement of the switch shaft  34  and the attached moving contact  206 , and helps to reduce the potential for the switch shaft  34  to rebound upon reaching its opening position. Such rebounding has the potential to cause the latching subassembly  22  to de-latch from the switch shaft  34 , which in turn can result in the unintentional re-closing of the switch  200 . The energy is stored in the hammer spring  28 , and to a lesser extent, in the springs  73 . The energy is used to unlatch the latching subassembly  22  from the switch shaft  34  during the subsequent re-closing of the switch  200 . 
       FIGS.  6  to  15    sequentially depict the damper and latching assembly  10  in various states during opening and closing of the switch  200 .  FIGS.  6  to  12    depict the assembly  10  as the switch  200  moves from its closed state to its open state. As depicted in  FIG.  6   , the switch  200  is fully closed. The switch shaft  34  is in its forward most, or closing position, so that electrical and mechanical contact can occur between the moving contact  204  and the stationary contact  206 . The latching subassembly  22  is in its most clockwise, or unlatched position. As can be seen in  FIG.  6   , the shaft  98  of the latching subassembly  22  is contacting the second planar surface  119  of the switch shaft  34 , preventing counterclockwise rotation of the shaft  98 ; and the shaft  98  is not interfering with the linear movement of the switch shaft  34  toward or away from its closing position. Also, the rearward portion  116  of the switch shaft  34  is not yet contacting the reset shaft  26 . 
     As also can be seen in  FIG.  6   , the reset lever  20  and the hammer  24  are in their most clockwise positions. Each of the lips  107  on the upper arms  104  of the latching assembly  122  is positioned within an associated one of the notches  69  in the hammer  24 . The lower end of the hammer spring  28  is in its most counterclockwise position, so that the winding of the hammer spring  28  is at its minimum. Although the hammer spring  28  is in a state of minimal energy storage, the hammer spring  28  nevertheless exerts a force on the hammer  24  by way of the roller  92 . At this point, the force exerted by the hammer spring  28  is biasing the hammer  24  in the clockwise direction. 
     Referring further to in  FIG.  6   , the spring  60  is forcing spring  27  to be slightly tensioned, so that the claw spring  27  exerts a slight clockwise rotation on the coupling member  30 . This tension causes the third pin  82  of the coupling member  30  to be disposed within the detents  68  in the first and second side members  62   a ,  62   b  of the hammer  24 , so that the hammer  24  is coupled to the reset lever  20  by way of the coupling member  30 . Each end of the first pin  78  is positioned at a first end of its associated first slot  47  in the first and second side members  40   a ,  40   b  of the reset lever  20 . Each end of the second pin  80  likewise is positioned at a first end of its associated second slot  48 . 
     Referring to  FIG.  7   , the switch  200  has begun its opening sequence. The switch shaft  34  has been moved to the left, from its closing position, by the secondary coil  216  during the slow-opening sequence of the switch  200 , or by the primary coil  212  during fast-opening sequence. The movement of the switch shaft  34  has caused the moving contact  204  to separate from the stationary contact  206 , thereby interrupting the flow of electric current through the switch  200 . The rearward-facing surface  121  of the switch shaft  34  has contacted the surface  130  of the center member  54  of the reset shaft  26 , and has imparted a counterclockwise rotation to the rest shaft  26  and the attached reset lever  20 . As can be seen in  FIG.  7   , the surface  121  of the switch shaft  34  is relatively large, and is angled to match the orientation of the surface  130  of the center member  54 . These features help to prevent deformation of the switch shaft  34  that otherwise could result from repeated openings of the switch  200 . 
     The switch shaft  34  initially moves to the left, from its closing position, by a distance of approximately one millimeter before the switch shaft  34  contacts the rest shaft  26 . This amount of movement is sufficient to permit the moving contact  204  and the stationary contact  206  to separate sufficiently to interrupt the flow of electric current through the switch  200 . Thus, because the switch shaft  34  does not contact any part of the damper and latching assembly  10  prior to separation of the moving and stationary contacts  204 ,  206 , the assembly  10  does not increase the time needed to separate the moving and stationary contacts  204 ,  206 . 
     In further reference to  FIG.  7   , the rotation of the reset lever  20 , in conjunction with the restraining effect of the hammer  24  on the third pin  82  of the coupling member  30 , has caused the coupling member  30  to rotate in a clockwise direction in relation to the reset lever  20 . The rotation of the coupling member  30 , in turn, causes the first and second pins  78 ,  80  to move away from the first ends of the respective first and second slots  47 ,  48  in the reset lever  20 . 
     Referring to  FIG.  8   , as the opening of the switch  200  progresses, the switch shaft  34  has moved further to the left, toward its opening position, imparting further counterclockwise rotation to the reset shaft  26  and the attached reset lever  20 . The reset lever  20  has imparted a counterclockwise rotation to the hammer  24  by way of the third pin  82  of the coupling member  30 , which has remained in the detents  68  and thus continues to couple the hammer  24  and the reset lever  20  by way of the coupling member  30 . Also, the coupling member  30  has continued to rotate in a clockwise direction in relation to the reset lever  20 , which in turn causes the first and second pins  78 ,  80  to move further away from the first ends of the respective first and second slots  47 ,  48  in the reset lever  20 . 
     In further reference to  FIG.  8   , the counterclockwise rotation of the hammer  24  has caused the arm  90  of the cam  86  and the lower end of the hammer spring  28  to rotate in a clockwise direction, winding the hammer spring  28 . The resistance of the hammer spring  28  to being wound dampens the rearward movement of the switch shaft  34 . Also, the energy being transferred to the hammer spring  28  as it is wound is stored in the hammer spring  28 , and as discussed below, is used to help unlatch the latching subassembly  22  from the switch shaft  34  when the switch  200  subsequently is re-closed. The counterclockwise rotation of the hammer  24  also has caused the springs  73  to stretch. The resistance of the springs  73  to being stretched exerts a further damping effect on the rearward movement of the switch shaft  34 . In addition, the counterclockwise rotation of the hammer  24  has caused the lips  107  of the hammer  24  to impart a counterclockwise rotation to the latching subassembly  22 , before the lips  107  disengage from the latching subassembly  22  at shown in  FIG.  8   . Also, it should be noted that the respective moment arms through which the opening force on the switch shaft  34  acts on the reset lever  20  and the hammer  26  during the opening sequence are relatively small. Thus, a substantial portion of the opening force is transmitted to, and dissipated in the sidewalls  218  of the switch  200  by way of the outer members  56  of the rest shaft  26 , and the mounting pin  70  of the hammer  24 , instead of being turned into torque. 
     As depicted in  FIG.  9   , the switch shaft  34  has advanced further toward is opening position as the opening of the switch  200  progresses, imparting further counterclockwise rotation to the latching subassembly  22  and the attached reset lever  20 . The voltage pulse that energizes the secondary coil  216  can be controlled so that, at about this point in the opening sequence, the force exerted by the secondary coil  216  to gradually decreases throughout the remainder of the opening sequence. This feature helps to slow the switch shaft  34  and reduce rebounding of the switch shaft  34  as the switch shaft  34  subsequently reaches the end of its leftward travel. 
     In further reference to  FIG.  9   , the reset lever  20  has imparted additional counterclockwise rotation to the hammer  24  by way of the third pin  82  of the coupling member  30 , which in turn has caused the first and second pins  78 ,  80  to approach the second ends of the respective first and second slots  47 ,  48  in the reset lever  20 . Also, the continued counterclockwise rotation of the hammer  24  has resulted in further winding of the hammer spring  28 , which has transferred additional energy to the hammer spring  28 . Also, the energy transfer to the spring  28  has continued to dampen the movement of the switch shaft  34  toward its opening position. 
     In further reference to  FIG.  9   , the first and second side members  62   a ,  62   b  of the hammer  24  have moved closer to the respective lower arms  106  of the latching subassembly  22 . Also, the leftward movement of the switch shaft  34  has positioned the relatively low first surface  118  of the switch shaft  34  directly below the shaft  98  the latching subassembly  22 , so that the switch shaft  34  no longer prevents rotation of the latching subassembly  22  in the counterclockwise direction, toward its latching position. 
     Referring to  FIG.  10   , the continued movement of the rest shaft  34  toward its opening position has caused the reset lever  20  impart additional counterclockwise rotation to the hammer  24  by way of the third pin  82  of the coupling member  30 . The rotation of the hammer  24  has caused the point of contact between the lower end of the hammer spring  28  and the roller  92  of the hammer  24  to move to an over-center over-toggle position in relation to the point of rotation of the hammer  24 , i.e., the point of contact between the hammer spring  28  and the hammer  24  now is located leftward of the axial centerline of the mounting pin  70  on which the first and second side members  62   a ,  62   b  rotate. Thus, the reactive force exerted by the hammer spring  28  on the hammer  24  now produces a counterclockwise moment on the hammer  24 , causing the hammer  24  to rotate toward its most counterclockwise angular position. 
     As further depicted in  FIG.  10   , the first and second pins  78 ,  80  have reached the second ends of the respective first and second slots  47 ,  48  in the reset lever  20 . At this point, further counterclockwise rotation of the reset lever  20  will cause the third pin  82  to begin disengaging from the coupling member  30 . Also, the lower ends of the first and second side members  62   a ,  62   b  of the hammer  24 , and the lower arms  106  of the latching subassembly  22  have contacted each other. Thus, further counterclockwise rotation of the hammer  24  will impart a counterclockwise rotation to the latching subassembly  22 . 
     Referring to  FIG.  11   , the switch shaft  34  is approaching the maximum extent of its leftward travel. The additional rotation imparted by the switch shaft  34  to the reset lever  20 , in conjunction with the now counterclockwise bias of the hammer spring  28  on the hammer  24 , have driven the hammer  28  to its most counterclockwise position. The rotation of the hammer  24 , in turn, has rotated the latching subassembly  22  counterclockwise, into its latching position. 
     As can be seen in  FIG.  11   , the lower ends of the first and second side members  62   a ,  62   b  of the hammer  24 , and the lower arms  106  of the latching subassembly  22  are restrained from further rotation by resilient bumpers  128  mounted on an adjacent stationary portion of the switch  200 . The bumpers  128  can be formed of viton or other suitable materials, and help to reduce or eliminate rebounding of the hammer  24  and the latching subassembly  22  as the hammer  24  and the latching subassembly  22  reach the ends of their respective counterclockwise rotation. 
     Referring further to  FIG.  11   , the springs  73  have been stretched to their maximum state of extension. The resulting force exerted by the springs  73  on the latching subassembly  22  further helps to reduce rebounding of the latching subassembly  22  as the latching subassembly  22  reaches the end of its counterclockwise rotation. 
     As also can be seen in  FIG.  11   , the continued rotation of the reset lever  20  after the hammer  24  has been stopped by the bumpers  128  causes the third pin  82  to begin to be drawn out of the detents  68  in the hammer  24 . 
     As depicted in  FIG.  12   , the switch  200  has reached the fully open and latched state. The latching subassembly  22  is in its latching position, and the secondary coil  216 , which has been deactivated, no longer exerts a leftward force on the switch shaft  34 . Upon deactivation of the secondary coil  216 , the switch shaft  34  has moved slightly to the right, into the opening position of the switch shaft  34 , due to the rightward bias of the closing spring assembly  207 . The switch shaft  34  is being restrained from further movement to the right by interference between the shaft  98  of the latching subassembly  22 , and the step  120  of the switch shaft  34 . The energy that has been stored in the hammer spring  28 , and to a lesser extent, the springs  73 , maintains the latching subassembly  22  securely in its latching position; and as discussed below, is subsequently used to assist in the opening of the switch  200 . 
     As also can be seen in  FIG.  12   , the third pin  82  of the coupling member  30  has been drawn out of the detents  68  in the hammer  24  by the rotation of the rest lever  20 . The reset lever  20  and the coupling member  30  thereby are decoupled from the hammer  24 , so that the switch  200  subsequently can close as described below. The coupling member  30  has come to rest on the cross member  81  of the hammer  24 , which restrains the coupling member  30  from further counterclockwise rotation. The tension exerted by the claw spring  27  on the coupling member  30  maintains the coupling member  30  in the orientation, relative to the reset lever  20 , depicted in  FIG.  12   , helping to ensure that the coupling member  30  does not prematurely re-engage with the hammer  24  and interfere with the subsequent closing of the switch  200  as discussed below. 
     Operation of the Assembly  10  During Closing of the Switch  200   
       FIGS.  13  to  15    illustrate the assembly  10  during closing of the switch  200 .  FIG.  6    depicts the switch  200  in its closed state.  FIG.  13    shows the assembly  10  at the start of the closing process. The closing solenoid  35  is activated at the start of the closing process, causing the solenoid  122  to rotate the paddle  124  in a counterclockwise direction, away from its closing position. As depicted in  FIG.  13   , the paddle  124  has contacted a pin  132  on the first side member  62   a  of the hammer  24 , and is about to initiate rotation of the hammer  24  in the clockwise direction. 
     Referring further to  FIG.  13   , the third pin  82  of the coupling member  30  is located within the relatively large openings  66  in the first and second side members  62   a ,  62   b  of the hammer  24 , and outside of the detents  68  in the first and second side members  62   a ,  62   b . Also, the tension exerted by the claw spring  27  on the coupling member  30  maintains the coupling member  30  in the orientation, relative to the reset lever  20 , depicted in  FIG.  13   , helping to ensure that the third pin  82  remains outside of the detents  68  until the final stage of the closing sequence. Thus, the hammer  24  is decoupled from the reset lever  20 , which is restrained from clockwise rotation by the latched switch shaft  34 . The hammer  24 , therefore, can rotate in the clockwise direction under the bias of the paddle  124 , without any constraint from the reset lever  20 , which in turn facilitates the unlatching of the switch shaft  34  as discussed below 
     As also can be seen in  FIG.  13   , the point of contact between the hammer spring  28  and the hammer  24  is still in an over-center position in relation to the point of rotation of the hammer  24 . Thus, the hammer spring  28  is still exerting a counterclockwise moment on the hammer  24 . 
     In further reference to  FIG.  13   , the secondary coil  216  has been activated with a low voltage pulse to move the switch shaft  34  slightly to the left, eliminating contact between the switch shaft  34  and the latching subassembly  22 , which in turn permits the latching subassembly  22  to rotate easily. Due to the bias of the closing spring assembly  207 , the force exerted by the switch shaft  34  on the latching subassembly  22  is relatively high, e.g., about 140 pounds. Providing a low-voltage pulse to the secondary coil  216  to momentarily decouple the switch shaft  34  from the latching subassembly  22  at the start of the closing sequence thus eliminates the high frictional force between the switch shaft  34  and the latching subassembly  22  that otherwise would need to be overcome by the closing solenoid  35  during the de-latching of the switch shaft  34 . 
     Referring to  FIG.  14   , the continued counterclockwise rotation of the paddle  124  has imparted a clockwise rotation to the hammer  24 . At this point, the rotation of the hammer  24  has caused the point of contact between the hammer spring  28  and the hammer  24  to move back from its over-center position, i.e., the point of contact between the hammer spring  28  and the hammer  24  now is located to the right of the axial centerline of the mounting pin  70 . Thus, the stored energy of the hammer spring  28  is now producing a clockwise moment on the hammer  24 . 
     In further reference to  FIG.  14   , the latching subassembly  22  is about to begin rotating from its latching position to its unlatching position. In particular, the rotation of the hammer  24  is about to cause the first and second side members  62   a ,  62   b  of the hammer  24  to contact the upper arms  104  of the latching subassembly  22 . Further clockwise rotation of the hammer  24  after this point thus imparts a corresponding clockwise rotation to the latching subassembly  22 , causing the latching subassembly  22  to rotate away from its latching position. Because the hammer spring  28  now is exerting a clockwise moment on the hammer  24 , and the hammer  24  is moving the latching subassembly  22  away from its latching position, using the energy that was stored in the hammer spring  28  during the opening of the switch  200 . Thus, the closing solenoid  35  only needs to rotate the hammer  24  back to its over-center position, after which the stored energy of the hammer spring  28  provide most, or all the force needed to complete the unlatching of the switch shaft  34 . The closing solenoid  35 , therefore, can be relatively small, helping to reduce the overall dimensions of the damper and latching assembly  10  and permitting the assembly  10  to fit within the very limited space constrains within the switch  10 . 
     As also can be seen in  FIG.  14   , the clockwise rotation of the hammer  24  in relation to the latching subassembly  22  has reduced the stretching of the springs  73 , thereby reducing the counterclockwise moment being exerted by the springs  73  on the latching subassembly  22 , which in turn makes it easier to rotate the latching subassembly  22  to its unlatching position. Also, the energy previously stored in the springs  73  resulted in a clockwise moment the hammer  24 , thus providing a limited degree of assistance in rotating the hammer  24  to the angular position shown in  FIG.  4   . 
     The energy stored in the springs  73  and the hammer spring  28  and being used in the unlatching process of the latching subassembly  22  is the energy that was transferred to the springs  73  and the hammer spring  28  during the opening of the switch  200 . As explained above, this energy transfer had dampened the movement of the switch shaft  34  and the moving contact  204  as the switch shaft  34  moved toward its opening position. The energy transfer to and from the springs  73  and the hammer spring  28  thus provides benefits during both the opening and the closing of the switch  200 . (It should be noted that the energy stored in the springs  73 , and the force exerted by the springs  73  to help close the switch  200 , are relatively low. The energy storage occurs primarily in the hammer spring  28 , and the force that assists in the closing the switch  200  results primarily from the energy stored in the hammer spring  28 .) 
     In further reference to  FIG.  14   , the secondary coil  216  remains activated at this point, and has driven the switch shaft  34  into contact with the center portion  52  of the reset shaft  26 . This contact prevents the reset shaft  26  and the reset lever  20  from rotating in the clockwise direction, which in turn helps to ensure that the third pin  82  remains disengaged from the hammer  24  and does not interfere with the clockwise rotation of the hammer  24 . 
     Referring to  FIG.  15   , the continued counterclockwise rotation of the paddle  124  of the closing solenoid  35  has caused the paddle  124  to reach its opening position, i.e., paddle  124  has reached the full extent of its counterclockwise rotation. The closing solenoid  35  is deactivated at this point. The hammer spring  28 , which continues to exert a clockwise moment on the hammer  24 , is now the sole driver of the clockwise rotation of the hammer  24  and the latching subassembly  22 . The switch shaft  34  continues to be driven to the right, from its locking position, by the secondary coil  216 , thereby maintaining a slight gap between the switch shaft  34  and the shaft  98  of the latching subassembly  22  so that the latching subassembly  22  can rotate without interference caused by friction between the switch shaft  34  and the shaft  98 . 
     As depicted in  FIG.  6   , the continued rotation of the hammer  24  under the bias of the hammer spring  28  has rotated the latching subassembly  22  to it unlatching position. The moment arm between the axis of rotation of the hammer  24  and the point at which the force of the hammer spring  28  is applied to the hammer  24  is the largest at this point, helping to ensure that the latching subassembly  22  is rotated fully to its unlatching position. Also, the secondary coil  216  has been deactivated, which has allowed unlatched switch shaft  34  to move to its closing position under the bias of the closing spring assembly  207 , thus re-establishing contact between the moving contact  204  and the stationary contact  206 . Also, the movement of the switch shaft  34  to its closing position has allowed the reset lever  26  to rotate clockwise under the bias of the spring  60 , which in turn has caused the third pin  82  of the coupling member  30  to re-enter the detents  68  in the first and second side members  62   a ,  62   b  the hammer  24  so that the reset lever  20  and the hammer  24  are again coupled for rotation together. 
     In further reference to  FIG.  6   , the springs  73  no longer are extended, and are not exerting any substantial tension on the hammer  24  and the latching subassembly  22 . Each lip  107  of the latching subassembly  22  has re-entered its associated notch  69  in the hammer  24 . And the paddle  124  of the closing solenoid  35  has returned to its closing position. The assembly  10  thus is ready for the subsequent re-opening of the switch  200 . 
     PARTS LIST 
     
         
         Damper and Latching System  10   
         Reset lever  20   
         Latching assembly  22   
         Hammer  24   
         Reset shaft  26   
         Hammer spring  28   
         Claw spring  27   
         Coupling member  30   
         Switch shaft  34   
         Closing solenoid  35   
         First side member  40   a    
         Second side member  40   b    
         Lower pin  42   
         Upper pin  44   
         Balance weight  46   
         Slot  47   
         Slot  48   
         End portions  50   
         Center portion  51   
         Flanges  53   
         Center member  54   
         Inner member  55   
         Outer member  56   
         E-clips  59   
         Spring  60   
         First side member  62   a    
         Second side member  62   b    
         Lower pin  63   
         Intermediate pin  64   
         Upper pin  65   
         Openings  66   
         Detents  68   
         Notch  69   
         Mounting pin  70   
         Springs  73   
         First side member  74   a    
         Second side member  74   b    
         Mounting pin  75   
         End portions  76   
         First pin  78   
         Second pin  80   
         Cross member  81   
         Third pin  82   
         Pin  84   
         Cam  86   
         Sleeve  88   
         Arm  90   
         Roller  92   
         Stop  94   
         Shaft  98   
         End portions  100   
         Hub  102   
         Upper arm  104   
         Lower arm  106   
         Lip  107   
         Projection  108   
         Forward portion  112   
         Intermediate portion  114   
         Rearward portion  116   
         First planar surface  118   
         Second planar surface  119   
         Step or lip  120   
         Rearward facing surface  121   
         Solenoid  122   
         Paddle  124   
         Bumpers  128   
         Surface  130   
         Pin  132   
         Switch  200   
         Switching assembly  202   
         Moving contact  204   
         Stationary contact  206   
         Closing spring assembly  207   
         Drive  208   
         Plunger  210   
         Primary coil  212   
         Secondary coil  216   
         Side plates  218