Patent Application
20150131210
The present invention relates to high-power electrical switches, and in particular to a flexible cable assembly 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 assembly 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 assembly 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 flexible cable is then attached to a movable portion of the handle to communicate this motion through the flexible cable to a slider held within the actuator frame. The slider may provide a collar capturing 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 end of the flexible cable of the flexible cable assembly may attached to the slider by means of a pair of opposed jam nuts attached to a threaded ferrule on one end of the flexible cable. The jam nuts are tightened against either side of a hole in the flange on the slider. Likewise, the sheath of the flexible cable assembly may be attached to the actuator frame by means of a pair of opposed jam nuts also tighten on opposite sides of a hole through a flange on the actuator frame. In both cases, the jam nuts serve the dual purpose of attaching the cable or the sheaf to corresponding structure and allowing adjustment of the relative points of attachment for “tuning” the remote actuation system.
“Tuning” adjusts the separation of the points of attachment of the flexible cable and the sheath to corresponding structure of the actuator and slide so that a given range of motion of the handle is translated to positions of the toggle operator of the circuit breaker sufficient fully switch the circuit breaker between its “on” and “oft” positions.
Assembly of the jam nuts to the respective attachment points of the slider and/or attachment frame requires that one jam nut be removed so that the threaded shaft holding the jam nuts can be inserted through the hole in the flange. The removed jam nut is then reinstalled and the two jam nuts adjusted for proper positioning. This process is cumbersome and time-consuming but allows the necessary tuning.
This latter step of tightening the jam nuts can also be difficult requiring that the actuator frame be partially disassembled and that the person making the assembly work within the close confines of that framework to loosen and tighten these two nuts. Once the two jam nuts are properly positioned they 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. Accordingly multiple trials may be required for proper adjustment.
The slider and adapter assembly may be formed of folded metal to provide the necessary mounting flanges needed for the jam nuts. These metal parts must be lubricated to prevent seizing of the sliding operation between few contact surfaces of the slider and the actuator frame. While these metal components are robust they are electrical conductors and must be used with care in the vicinity of electrical circuitry and with consideration of conduction from the actuator through the flexible cable to the handle and the cabinet.
The present invention provides a remote actuator system that may be more readily manufactured while still providing for the necessary “tuning” of the flexible cable assembly. In particular, the invention provides a slide and actuator frame element that may incorporate slots receiving flanged features on the flexible cable and sheath. During manufacture, the flexible cable may simply be dropped into the actuator frame with the flanged features being received by corresponding slots with no necessary removal or tightening of jam nuts. A multi surface engagement between the slider and the actuator frame allows reduced or lubricant free operation of these inter-engaging components when manufactured from thermoplastic materials. A snap-fit cover retains the flexible cable assembly within the actuator frame without the need to install multiple screws or the like.
Specifically, in one embodiment, the invention provides a remote switching assembly for use with an electrical switch having a switch operator movable along an actuation axis. The remote switching assembly includes an actuator frame presenting a longitudinal channel extending along a longitudinal axis and attachment elements for attaching the actuator frame to a housing of an electrical switch adjacent to the switch operator so that the longitudinal axis is substantially parallel to the actuation axis. A slider fits within the longitudinal channel of the actuator frame to slide therein along the longitudinal axis. A flexible cable assembly providing a sheath surrounding a flexible cable, the sheath and the flexible cable providing flange elements attached thereto and having features extending radially from axes of extension of the sheath and flexible cable. The actuator frame may provides a key way extending across the longitudinal axis receiving the flange element of the sheath to retain the sheath against movement in the longitudinal direction with respect to the actuator frame and the slider may provide a key way extending across the longitudinal axis receiving the flange element of the flexible cable to retain the flexible cable against movement in the longitudinal direction with respect to the slider.
It is thus a feature of at least one embodiment of the invention to provide a method of rapidly assembling an actuator frame that eliminates the laborious removal, adjustment, and torquing of jam nuts.
The key way in the actuator frame may provide two slots opposed perpendicularly to the longitudinal axis to retain opposed surfaces of the flange elements.
It is thus a feature of at least one embodiment of the invention to provide a slot system that distributes actuation forces to allow for robust construction of the slider and actuator frame from thermoplastic materials into which the necessary slots may be formed.
One flange element may be a flange of a threaded fastener attached to a threaded terminator on the sheath.
It is thus a feature of at least one embodiment of the invention to provide an attachment method compatible with adjustment of at least one flange element for tuning the remote actuation system.
The flange element may be further sized to threadably rotate about the threaded terminator within the key way.
It is thus a feature of at least one embodiment of the invention to permit tuning of the remote actuation system after assembly of the flexible cable.
One flange element may be a lock nut fixedly attached to a threaded end of the flexible cable.
It is thus a feature of at least one embodiment of the invention to simplify assembly by limiting adjustment to only the attachment point of the sheath. It is another feature of at least one embodiment to provide a simple method of attaching a flange element to the flexible cable.
The actuator frame may provide two components of an attachable blocking element and a channel element where the blocking element fits over at least one of the key ways of the slider and actuator frame to prevent removal of at least one of the flange elements of the sheath and cable when the removable blocking element is attached.
It is thus a feature of at least one embodiment of the invention to provide a simple method of retaining the flange elements against dislodgment.
The blocking element may fit over both of the key ways of the slider and actuator frame to prevent removal of at both flange elements of the sheath and cable when the removable blocking element is attached.
It is thus a feature released one embodiment of the invention to simultaneously lock in both flange elements.
The removable blocking element may be a cover fitting over the channel in the channel element of the actuator frame.
It is thus a feature of at least one embodiment of the invention to lock in the flange elements and to cover the slider against contamination or interference.
The cover may attach to the actuator frame by inter-engaging hook elements.
It is thus a feature of at least one embodiment of the invention to provide a simple fastener-less assembly technique for the cover.
The cover may include a snap detent preventing removal of the cover without manipulation of the snap detent element by a tool.
It is thus a feature of at least one embodiment of the invention to prevent inadvertent removal of the cover without requiring retaining screws or the like.
The cover may engage the hook elements by movement with respect to the channel in the longitudinal direction.
It is thus a feature of at least one embodiment of the invention to provide a removal direction that is not promoted by forces of the flange elements in dislodgment.
The slider element may include opposed first and second channels receiving corresponding rails in the actuator frame so that the sliding element has sliding contact between the first and second channels and the corresponding rails and between outer walls of the slider element and walls of the channel.
It is thus a feature of at least one embodiment of the invention to provide forced distributed construction allowing the actuation channel and slider to be constructed robustly of thermoplastic material. It is another feature of at least one embodiment of the invention to lessen the need for lubricants to prevent camming or jamming of the slider.
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 actuator 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 actuator 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 actuator frame 46 may be visually determined through the actuator frame cover 58. Generally, the actuator frame cover 58 may be attached to the actuator 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.
