Patent Application
20150131208
The present invention relates to high-power electrical switches, and in particular to a flexible cable operator for remotely actuating electrical switches such as circuit breakers.
High-power electrical circuitry is normally placed inside a metal cabinet to protect the electrical circuitry from the external environment and to shield users from potential hazards associated with the operation of the circuitry.
Often the cabinet provides a handle that serves both to lock a cabinet door and to disconnect electrical power from the interior circuitry before the door is opened. The handle may communicate through a flexible cable operator with a switch inside the cabinet, for example, a circuit breaker, so that when the handle is moved to allow opening of the cabinet door, the circuit breaker is also opened, removing electrical power from the interior circuitry. This feature is normally subject to the mechanical override in the event that the cabinet must be operated with the door open and the circuitry live.
A flexible cable operator provides a substantially incompressible sheath through which a flexible cable may slide. Opposite ends of the sheath are fixed respectively to a stationary structure of the handle and an actuator frame attached to the circuit breaker housing. One end of the cable is then attached to a movable portion of the handle to communicate this motion through the cable to a slider held within the actuator frame. The slider may provide a collar receiving a toggle operator of the circuit breaker to move the circuit breaker toggle between an “on” and “off” position with movement of the flexible cable by the handle.
The flexible cable must normally be “tuned” so that the motion at the circuit breaker is sufficient to move the circuit breaker toggle fully between on and off positions when the handle is moved between on and off positions. This tuning is normally accomplished by adjusting a pair of opposed “jam nuts” attached to a threaded barrel on one end of the flexible cable sheath. The jam nuts capture a flange of the actuator frame between them. By loosening one nut and tightening the other, the point of attachment of the sheath to the stationary actuator framework may be shifted to properly center the actuation range of the flexible cable with respect to the operating range of the circuit breaker toggle.
Adjusting these jam nuts can be relatively difficult requiring partial disassembly of the actuator framework and working within the close confines of that framework to loosen and tighten these two nuts. Once the end of the sheath is properly positioned, the two jam nuts must be tightened together using torque-controlled tools to ensure that the connection does not inadvertently loosen during vibration or use and to ensure that the torque is not so high as to damage the threaded barrel on the end of the sheath causing the sheath to separate from the actuator.
After moving the jam nuts, it can be difficult to determine whether the adjustment is correct because the handle may not be operated with the jam nuts loose such as would allow the sheath to move freely in this position tested. Accordingly multiple trials may be required for proper adjustment.
The invention provides an improved actuator allowing single point adjustment of the attachment of the flexible cable sheath to the actuator housing, eliminating the need to loosen, adjust and tighten pairs of jam nuts to precise torques. A visual gauge may be provided to assist in this adjustment process.
Specifically, the invention provides a switching apparatus for an electrical switch of the type that may be disposed in a cabinet, where the electrical switch has a toggle operator extending from a front of a housing of the electrical switch movable along an actuation axis to switch the electrical switch between an on and off state. The invention includes an actuator frame that can be attached to the housing of the electrical switch proximate to the toggle operator and a slider held by the actuator frame to slide along the actuation axis. The slider provides a collar receiving the toggle operator when the stationary actuator frame is fixed to the housing of the electrical switch, so that movement of the slider along the actuation axis may switch the toggle operator between the on and off states. An actuator cable has an outer sheath and inner flexible cable, and a first end of the outer sheath is attached to one end of the actuator frame so that the inner flexible cable may extend from the first end along the actuation axis, and a first end of the inner flexible cable attached to the slider may move the slider with movement of the inner flexible cable. The attachment between the first end of the outer sheath and the actuator frame provides a threaded ferrule at the first end of the actuator sheath receiving a threaded fastener. A portion of the threaded fastener is received within a pocket on the actuator frame sized to permit rotation of the threaded fastener about the threaded ferrule within the pocket while preventing translation of the threaded fastener along the axis with respect to the actuator frame.
It is thus a feature of at least one embodiment of the invention to eliminate the need for complex adjustment of jam nuts in tuning a remote actuator for an electronic switch.
The threaded fastener may provide a substantially circular disk portion having opposed faces abutting corresponding opposed faces of the pocket.
It is thus a feature of at least one embodiment of the invention to provide an engagement surface that offers low resistance rotation even in the presence of translated forces.
The threaded fastener may include a nut portion coaxially attached to the circular disk portion and providing wrench-engaging flats.
It is thus a feature of at least one embodiment of the invention to provide a separate feature better optimized to the different requirements of turning the threaded fastener and retaining the threaded fastener.
The nut portion is a hex nut with three-quarter inch separated flats (19 mm).
It is thus a feature of at least one embodiment of the invention to provide a nut fitting standard English and metric wrenches for ready field adjustment.
The pocket may provide a U-shaped slot conforming to an outer periphery of the substantially circular disk portion of the threaded fastener.
It is thus a feature of at least one embodiment of the invention to provide an engagement feature in the actuation frame that offers good support to the threaded fastener as may be implemented in a thermoplastic material or the like.
The switching apparatus may further include an actuator frame cover fitting over the pocket to retain the circular disk portion within the pocket and the nut portion may extend axially beyond the actuator frame and actuator frame cover when fitting over the pocket to be accessible with a wrench.
It is thus a feature of at least one embodiment of the invention to retain and protect the components of the actuator assembly while allowing ready tuning of the actuator assembly in its assembled form. By combining a nut feature with a captured flange, the nut may be fully exposed for access.
At least one of the actuator frame and actuator frame cover may provide a viewable scale proximate to a fiducial feature of the slider, the scale indicating a first range of positions of the slider corresponding to switching of the toggle operator in the on state and a second range of positions corresponding to switching of the toggle operator in the off state.
It is thus a feature of at least one embodiment of the invention to provide immediate visual guidance of the information needed to properly tune the actuator assembly when it is in its fully assembled state.
The first range of operator positions may be marked in red with at least one of the symbols for I and on and the second range of operator positions is marked in green with at least one of the symbols for O, off, or reset.
It is thus a feature of at least one embodiment of the invention to provide a visual indicator that also functions to indicate state and proper operation of the actuator assembly.
The scale may further provide a range of positions between the first and second range of positions indicating the position where the toggle operator is not well defined in either of the on or off state.
It is thus a feature of at least one embodiment of the invention to guide the operator when tuning the actuator assembly to a tuning that insures proper operation even in the face of manufacturing tolerance stack up.
The scale may be on the actuator frame cover and the fiducial feature may be a finger extending from the slider through a slot in the actuator frame cover or along either left or right sides of the frame cover adjacent to the viewable scale.
It is thus a feature of at least one embodiment of the invention to provide an indication of operating status of the actuator assembly that may be readily viewed in most installation configurations and that directly reveals the state of the internal slider.
The actuator frame cover may engage the actuator frame by an axial slidable engagement of corresponding hooks.
It is thus a feature of at least one embodiment of the invention to provide a tuning system that accommodates some axial position tolerance implicit in a sliding engagement system.
At least a portion of the threaded fastener may be exposed through the assembled actuator frame cover and actuator frame at a position to be manipulated by a user viewing the scale.
It is thus a feature of at least one embodiment of the invention to allow the scale to be used during the tuning operation.
The actuator frame may be injected molded thermoplastic.
It is thus a feature of at least one embodiment of the invention to provide a design that accommodates fabrication and an electrically nonconductive polymer.
The actuator frame may include outer flange portions having holes for receiving machine screws to attach the actuator frame to the electrical switch.
It is thus a feature of at least one embodiment of the invention to provide a mounting system that accommodates a variety of different electrical switches while positively locating the actuator assembly with respect to the electrical switch simplified assembly in tuning.
The above aspects of the invention are not intended, to define the scope of the invention for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof and in which there is shown by way of illustration, and not limitation, a preferred embodiment of the invention. Such embodiment does not define the scope of the invention and reference must be made therefore to the claims for this purpose.
Reference is hereby made to the following figures in which like reference numerals correspond to like elements throughout, and in which:
Referring now to
The front panel 18 may be fixed to one edge of the cabinet 10 against a left side wall 16 and spanning an upper and lower side wall 16 and may support a handle assembly 24. The handle assembly 24 may include a frame 26 supporting a pivoting handle 28 which may swing between an upper “on” position and a lower “off” position (the latter shown in
Referring also to
Generally, the movable handle 28 controls an actuation linkage 34 attached to a portion of the handle frame 26 inside the cabinet 10. This actuation linkage 34 in turn may be attached to a flexible cable 36 fitting within a tubular cable sheath 38 together forming a flexible cable assembly 40. The end of the sheath at the handle assembly 24 may be fixed by a clamp 41 to the handle frame 26 so that movement of the actuation linkage 34 by the handle 28 slides the flexible cable 36 within the sheath 38.
As is generally understood in the art, the flexible cable 36 and tubular cable sheath 38 may be relatively freely flexed across their axes of extension but are substantially resistant to changes in dimension in tension or compression along their axes of extension to efficiently transmit the relative motion between the flexible cable 36 and the sheath 38 to a remote location. Generally, motion of the handle 28 through its entire range will provide for a relative movement between the flexible cable 36 and the cable sheath 38 of a predefined distance 42 as will be discussed further below. The actuation linkage 34 controls the relationship between the movement of the handle 28 and the desired predefined distance 42 of the flexible cable 36.
Referring again to
Referring now to
The cable assembly 40 may attach to a lower end of the actuator frame 46 (as will be discussed below) so that the flexible cable 36 extending through the sheath 38 may pass into the channel 48 along the actuation axis 50 to attach to the slider 52. As so assembled, movement of the flexible cable 36 will move the slider 52 along the actuation axis 50 within the actuation frame 46.
When the slider 52 is within the channel 48 and the cable assembly 40 attached to the actuator frame 46, an actuator frame cover 58 may be installed to cover the upper opening of the channel 48 and a portion of the cable assembly 40 within that channel 48. With the actuator frame cover 58 in place, the collar 54 remains uncovered, projecting from the side of the actuation frame 46.
A fiducial feature 59 of the slider 52 may project upward through a slot 60 in the actuator frame cover 58 so that the relative position of the slider 52 within the actuation frame 46 may be visually determined through the actuator frame cover 58. Generally, the actuator frame cover 38 may be attached to the actuation frame 46 by sliding engagement between a set of downwardly extending hooks 62 on the actuator frame cover 58 and laterally outwardly extending hooks 64 at an upper edge of the channel 48 of the actuator frame 46, as will be discussed in more detail below.
Referring also to
This inter-engagement of the toggle operator 74 is such as to allow movement of the slider 52 and collar 54 to fully actuate electrical switch 14, moving the toggle operator 74 between an “on” position in which electrical current is conducted through the electrical switch 14 and “off” position in which electrical current is interrupted, when the slider 52 moves by the predefined distance 42.
Each of the slider 52, actuator frame cover 58, and actuator frame 46 may be constructed of injection molded thermoplastic having a high electrical dielectric to resist electrical conduction through these components to the flexible cable 36 should electrical power be applied to any of these components.
Referring now to
The radially projecting circular flange 82 may be substantially cylindrical like a washer and of greater diameter than the diameter of a circle circumscribing the flats of the hex nut 80. For example, the circular flange 82 may have a diameter of 1 inch and an axial thickness of approximately 9/16 of an inch. The lower end of the actuator frame 46 may provide a U-shaped groove 84 of equal diameter to the circular flange 82 that may receive the circular flange 82 while allowing the hex nut 80 to extend outward from the actuator frame 46 to be readily accessible. The U-shaped groove 84 is sized to permit free rotation of the circular flange 82 therein but to substantially resist translation of the circular flange along the actuation axis 50.
It will be appreciated that rotation of the threaded fastener 78 will move the threaded fastener along the threaded ferrule 76 adjusting the relative point of attachment of the sheath 38 to the actuator frame 46 as will be discussed further below. When the actuator frame cover 58 of
Referring still to
Referring now also to
Referring now to
The handle 28 may then be moved to the “on” position and the on extreme point 106 established with respect to the scale 103. The predefined distance 42 will be the distance between the on extreme point 106 and the off extreme point 102. The threaded fastener 78 may then be adjusted to move a center point 108 between the off extreme point 102 and on extreme point 106 to be approximately centered at a center point 110 of the visual scale 104. The tuned assembly is then sent to the user who normally need not adjust the threaded fastener 78 on-site.
The visual scale 104 includes a dead zone 112 about the center point 110 indicating the region where the position of the toggle operator 74 shown in
Referring now to
In that assembly process conducted at the manufacturer, the actuator frame 46 is first attached to the switch 14 as discussed above with respect to
As indicated by process block 122, the threaded fastener 78 may then be assembled onto the threaded ferrule 76 as shown in
At process block 124, the slider 52 may be inserted into the channel 48 so that the collar 54 fits around the toggle operator 74 as shown in
Referring now to
The actuator frame cover 58 may include a downwardly extending lock tab 130 that passes over a locking ramp 132 on an inner vertical wall of the actuator frame 46 near groove 84. As shown in
Referring again to
Referring now to
Alternatively, in a second position 139b, the aperture 138 may be moved to position 134′ so that the shank 136 of the padlock 137 may pass adjacent to an upper wall of the slider 52 to prevent movement of the slider 52 toward the “on” position, yet without requiring slot 140.
As shown in
Referring to
A lower portion of the collar 54 may be expanded in a flange 146 to provide a stabilizing surface that rests against the upper surface of the switch 14 for improved stability. Generally, in the locked position, the machine screws 66 (shown in
Certain terminology is used herein for purposes of reference only and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.
When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.
