Patent Publication Number: US-9423818-B2

Title: Over-center handle mechanism for increased tactile feedback on a rotary actuator

Description:
RELATED CASES 
     The present application claims priority under 35 U.S.C. §119(e) based on U.S. Provisional Application Ser. No. 61/935,544 filed on Feb. 4, 2014, which is incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The present disclosure is related to an over center handle mechanism with a rotary actuator for operating electrical equipment housed in an electrical enclosure, and more particularly, to a spring assembly to adjust and control angular torque characteristic of the rotary actuator of an over-center handle mechanism. 
     BACKGROUND 
     There are many kinds of electrical equipment that, for safety considerations, are located inside an electrical enclosure and operated using a through-door handle with appropriate linkage to the equipment. For ergonomic reasons, electrical enclosures are often equipped with a large through-door handle to operate the electrical equipment, which can include for example a. circuit breaker(s), an electrical switch(es) or components that are part of a power distribution or protection system. Since the electrical equipment may not be originally designed specifically for operation with the through-door handle, the angular torque characteristics of the through-door handle may be poorly matched tier operating the electrical equipment that is housed in the electrical enclosure. 
     SUMMARY 
     An improved over-center handle mechanism is provided for operating electrical equipment, such as an electrical switch or circuit breaker, housed in an electrical enclosure using a through-door handle from outside of the electrical enclosure. For example, the over-center handle mechanism can include an adaptor knob, a rotary actuator and a through-door handle (e.g., an external handle on the exterior of an electrical enclosure). The adaptor knob interfaces with the electrical equipment. For example, the adaptor knob can include an aperture configured to slide over a circuit breaker or switch handle. The rotary actuator is connected to the adaptor knob and includes a cam. The through-door handle is used to operate the rotary actuator, which in turn operates the electrical equipment via the adaptor knob. To optimize an angular torque or snap “feeling” at the through-door handle, the over-center handle mechanism further includes a spring to provide an opposing force against movement of the cam of the rotary actuator, and thus, the through-door handle when operating the electrical equipment to different positions (e.g., OFF or ON position). A solid lubricant of PTFE can be provided as an interface between the cam and the spring to reduce friction therebetween. Accordingly, the over-center handle mechanism is able to provide for increased tactile feedback on the rotary actuator, and thus, the through-door handle. Furthermore, the over-center handle mechanism can be configured with a smaller form factor and minimized part count. 
     The spring operates as both a cantilever spring and a torsion spring at the same time. To function in this manner the spring has a generally U-shaped portion including two generally parallel legs that functions as torsion springs and two generally parallel arms extending generally perpendicularly from the two parallel legs of the torsion spring portion which function as a cantilever springs The torsion spring portion is confined at a point immediately adjacent to the point at which the cantilever spring portion begins such that the distance between the two generally parallel legs of the torsion spring portion can not increase. Each extending arm of the cantilever spring portion engages an outer surface of the cam and can have a PTFE sleeve to provide an interface between the cam and the spring. When the through-door handle is operated in either the clockwise or counter-clockwise direction to rotate the cam of the rotary actuator, the extending arms of the spring provide an opposing force against the outer cam surface of the rotating cam. The cam can have a substantially quadrilateral cross-section (e.g., rectangular, parallelogram, etc.), with the two extending arms of the spring positioned adjacent to and in contact with opposite sides of the cam. The cross-sectional shape of the cam can be configured to provide a desired torque profile when operating the through-door handle between different positions, such as between ON and OFF positions for the electrical equipment. For example, by configuring the shape of the cam and the placement of the spring, it is possible to provide two different torque or snap “feelings” for two different operations, e.g., when turning the electrical equipment from the OFF to ON position or from the ON to OFF position. Thus, the typical over-center feel of operation for an electrical switch may be maintained by appropriate selection of the cam faces. To provide for different angular torque profiles, the cam can be configured with an asymmetrical cross-sectional shape or area. Instead of a cantilever spring, a torsion spring can also be designed with two deflectable extending arms for use with the over-center handle mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description of the various exemplary embodiments is explained in conjunction with the appended drawings, in which: 
         FIG. 1  illustrates a perspective view of an over-center handle mechanism for operating electrical equipment housed inside of an electrical enclosure, the mechanism including an adaptor knob to interface with the electrical equipment, a rotary actuator, a spring, and a housing (currently phantomed), in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 2  illustrates an exploded view of the components of the over-center handle mechanism of  FIG. 1 . 
         FIG. 3  illustrates a cut-away view of the rotary actuator of the over-center handle mechanism of  FIG. 1  with the housing (currently phantomed), particularly showing the arrangement between the spring and an outer cam surface of a cam of the rotary actuator in order to adjust an angular torque profile of the over-center handle mechanism. 
         FIG. 4  illustrates a cross-sectional view of the rotary actuator for the over-center handle mechanism in  FIG. 1 , with a cam of the rotary actuator having a cross-sectional shape in the form of a parallelogram, in accordance with another embodiment of the present disclosure. 
         FIG. 5  illustrates a side view of a rotary actuator for the over-center handle mechanism in  FIG. 1 . 
         FIG. 6  illustrates a cross sectional view of the cam of the rotary actuator in  FIG. 4  in relation to the spring of the over-center handle mechanism of  FIG. 1 , when the actuator is rotatably adjusted to the OFF position. 
         FIG. 7  illustrates a cross sectional view of the cam of the rotary actuator in  FIG. 4  in relation to the spring of the over-center handle mechanism of  FIG. 1 , when the actuator is rotatably adjusted between the OFF and ON positions. 
         FIG. 8  illustrates a cross sectional view of the cam of the rotary actuator in  FIG. 4  in relation to the spring of the over-center handle mechanism of  FIG. 1 , when the actuator is rotatably adjusted to the ON position. 
     
    
    
     DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
     The present disclosure describes an over-center handle mechanism  100  for operating electrical equipment (e.g., an electrical switch, a circuit breaker or relay) housed in an electrical enclosure. The over-center handle mechanism  100  includes an adaptor knob  130  to interface with the electrical equipment, a rotary actuator  170  connected to the adaptor knob  130 , and a spring  150 . A through-door handle, which is outside of the enclosure, is operatively connected to the rotary actuator  170  to operate the electrical equipment, via the rotary actuator  170  and the adaptor knob  130 . The spring  150  is arranged to apply an opposing force (e.g., a spring force) against an outer cam surface of a cam  300  on the rotary actuator  170  to adjust and control an angular torque characteristic of the rotary actuator  170 , and thus, the through-door handle connected thereto. An example of the over-center handle mechanism  100  is described in greater detail below with reference to the figures. 
       FIG. 1  illustrates an over-center handle mechanism  100  for operating electrical equipment housed in an electrical enclosure.  FIG. 2  illustrates an exploded view of the components of the over-center handle mechanism  100 . As shown in  FIGS. 1 and 2 , the over-center handle mechanism  100  includes an adaptor knob  130 , a spring  150  and a rotary actuator  170 , which are assembled onto a housing  110 . The over-center handle mechanism  100  can also include a through-door handle (e.g., an external handle on the exterior of an electrical enclosure). The through-door handle is used to operate the rotary actuator  170 , which in turn operates the electrical equipment via the adaptor knob  130 . 
     The housing  110  includes a first side  112  and an opposite second side  114 , with a through-hole  122  extending therebetween. The adaptor knob  130  is positioned on the first side  112 , and the rotary actuator  170  is positioned on the second side  114 . The housing  110  includes a spring slot  120  to receive and mount a portion of the spring  150  onto the housing relative to the rotary actuator  170 . The spring slot  120  extends through the second side  114  of the housing  110  over and proximate to the through-hole  122 . The housing  110  is mountable inside of an electrical enclosure. 
     The adaptor knob  130  interfaces with the electrical equipment, such as, for example, an electrical switch, a circuit breaker or relay, which is housed in an electrical enclosure. The adaptor knob  130  can include a first side  132  and a second side  134 . The adaptor knob  130  is configured on the first side  132  to interact, directly or indirectly, with the electrical equipment. For example, the adaptor knob  130  can include an aperture, which is configured to slide over an operating handle of the electrical equipment, on the first side  132 . The adaptor knob  130  includes an adaptor knob shaft  136  extending generally perpendicularly from the second side  134  along the rotational axis of the adaptor knob  130 . In this example, the adaptor knob shaft  136  has a rectangular cross-section. The adaptor knob shaft  136  includes one or more latches  138  (e.g., latching ears) at its distal end for connecting the adaptor knob  130  to the rotary actuator  170 , when the adaptor knob shaft  136  is inserted into a socket  320  of the rotary actuator  170 . 
     The rotary actuator  170  includes a first end  172  and an opposite second end  174 . The rotary actuator  170  is connected on the first end  172  to the adaptor knob  130 , via the through-hole  122  of the housing  110 . The rotary actuator  170  also includes a shaft opening  178  on the second end  174  to receive a shaft or other linkage assembly (not shown), which is operatively connected to the through-door handle. The rotary operator  170  can include a bolt hole  179  through which to receive a bolt assembly to secure the shaft in the shaft opening  178  of the rotary actuator  170 . The bolt assembly can include a bolt  180 , washer  182  and a nut  184 . 
     The rotary actuator  170  further includes a first disc-shaped wall  192  on the first end  172  and an opposite second disc-shaped wall  194  on the second end  174 . The first wall  192  and the second wall  194  are spaced apart, and arranged substantially perpendicular to a rotational axis of the rotary actuator, when rotatably mounted to the housing  110 . 
     As further shown in  FIG. 3 , the rotary actuator  170  also includes a cam  300 , which extends along the rotational axis and forms a bridge to connect the first wall  192  to the second wall  194 . The socket  320  extends from the first end  172  of the rotary actuator  170  through the cam  300 , and is configured to receive the shaft  136  of the adaptor knob  130  (see e.g., in  FIG. 2 ). The socket  320  and surrounding cam  300  can have an asymmetrical cross-sectional shape to provide and control an over-travel range between the adaptor knob  130  and the rotary actuator  170 , and thus, the through-door handle connected thereto. Thus, the dimension of the cam  300 , socket  320  and the cross-sectional shape of the adaptor knob shaft  136  can be configurable to control an over-travel range in a clockwise or counter-clockwise direction for the rotary actuator  170 . 
     In  FIG. 3 , the cam  300  has a substantially quadrilateral cross-sectional shape. The cam  300  includes a first U-shaped cam portion  310 A and a second U-shaped cam portion  310 B, which are spaced apart to form two opposing latch slots  312  in the cam  300 . Each of the latch slots  312  are configured to receive a respective latch  138 , as shown in  FIG. 2 , when the adaptor knob shaft  136  of the adaptor knob  130  is fully engaged in the socket  320  of the rotary actuator  170 , to securely connect the adaptor knob  130  and the rotary actuator  170  together. 
     To adjust and control an angular torque characteristic (e.g., angular torque profile), the over-center handle mechanism  100  employs the spring  150 , as shown in  FIG. 3 , which has a portion mounted and supported in the spring slot  120  of the housing  110 . The spring  150  is used to apply force against the cam surfaces to oppose movement (e.g., rotation) of the rotary actuator  170 , and thus, of the other connected components such as the adaptor knob  130  and the through-door handle during operation. The spring  150  has one or more deflectable portions that are positioned adjacent to and in contact with the outer cam surface of the cam  300 , to apply a spring force against the outer cam surface. Thus, it is possible to optimize an angular torque feeling at the through-door handle, by way of the interaction between the spring  150  and the cam  300  of the rotary actuator  170 . 
     As shown in  FIG. 3 , the cam  300  can have a substantially symmetrical cross-sectional shape, in the form of a rectangle, which provides for the same torque profile when operating the rotary actuator  170 , and thus the through-door handle, in a clockwise direction (e.g., from an OFF to ON position) or a counter-clockwise direction (e.g., from an ON to OFF position). The cam  300 , however, can be designed with an asymmetrical cross-sectional shape to provide different angular torque profiles when operating the rotary actuator in a clockwise direction versus counter-clockwise direction. Another example of the cam  300  of the rotary actuator  170  is shown in  FIG. 4 , with a cross-sectional shape in the form of a parallelogram instead of a rectangle. 
       FIG. 5  illustrates a side view of the rotary actuator  170 , which includes the first end  172  and the second end  174 . The cam  300  is shown as being connected between the first and second walls  192  and  194 , and includes the latch slot  312 . A space  180  for receiving the extending arms  154  of spring  150  is also shown between the first and second walls  192  and  194 . 
       FIGS. 6-8  illustrate the relationship of the extending arms  154  of the spring  150  and the outer surface of the cam  300  (e.g., the cam  300  in in  FIG. 4 ), during operation of the through-door handle, and thus, the rotary actuator  170  between an OFF position and an ON position. The adaptor knob shaft  136  is engaged in the rotary actuator  170  (e.g., in the socket  320  of  FIG. 3 ). For example, in  FIG. 6 , the rotary actuator  170  is shown in the OFF position, with the extending arms  154  in a substantially non-deflected state. At this position, the extending arms  154  can apply little or no spring force against the outer surface of the cam  300 .  FIG. 7  shows that the rotary actuator  170  is between the OFF and ON position, with the extending arms  154  in a substantial deflected state and applying substantial spring force against the outer surface of the cam  300 . In  FIG. 8 , the rotary actuator  170  is shown in the ON position, with the extending arms  154  in a substantially non-deflected state. As previously discussed, the cross-sectional shape of the cam  300  can be designed to control the torque profile to provide the same or different angular torque feeling when operating the through-door handle or the rotary actuator  170  to different positions, such as an ON position or an OFF position for the electrical equipment. 
     The over-center handle mechanism  100 , as described herein, is provided as an example. The cam  300  of the rotary actuator  170  can be configured with other types of cross-sectional shapes, such as other polygon shapes, which are symmetrical or asymmetrical. Furthermore, the housing  110  can be configured in any suitable shape and dimension to mount the adaptor knob  130 , the spring  150  and the rotary actuator  170 . For example, the housing  110  can simply be a plate with a through-hole  122  and a spring slot  120 . 
     Words of degree, such as “about”, “substantially”, and the like are used herein in the sense of “at, or nearly at, when given the manufacturing, design, and material tolerances inherent in the stated circumstances” and are used to prevent the unscrupulous infringer from unfairly taking advantage of the invention disclosure where exact or absolute figures and operational or structural relationships are stated as an aid to understanding the invention. 
     While particular embodiments and applications of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the invention.