Patent Application
20150077203
Embodiments described herein relate generally to magnetic control devices, and more particularly to systems, methods, and devices for magnetic control devices for enclosures.
When certain control devices (e.g., pushbuttons, switches) are integrated with a receptacle housing and enclosure system (simply called an “enclosure” herein), there is at least one aperture that is made in the enclosure to accommodate the control device. When the enclosure is located in certain environments, then the enclosure must comply with one or more of a number of standards and/or requirements. Examples of such environments can include, but are not limited to, military applications, onboard ships, assembly plants, power plants, oil refineries, and petrochemical plants. At times, the equipment located inside such enclosure is used to control motors and other industrial equipment.
In order for an enclosure to meet certain standards and requirements, the gap between the enclosure and the control device must be sealed within certain tolerances. If the gap is not properly maintained, then a point of environmental ingress and/or loss of integrity of the enclosure can result.
In general, in one aspect, the disclosure relates to control device for an enclosure. The control device can include a first portion positioned proximate to a back side of an enclosure surface of the enclosure. The first portion of the control device can include a plunger having a proximal end and a distal end, where the plunger has a first position toward the enclosure surface and a second position away from the enclosure surface, and where the proximal end is adjacent to the enclosure surface. The first portion of the control device can also include a first magnet having a first polarity and disposed at the proximal end of the plunger. The first portion of the control device can further include at least one contact in communication with the distal end of the plunger, where the at least one contact has a first state and a second state. The control device can also include a second portion positioned proximate to a front side of the enclosure surface. The second portion of the control device can include a second magnet having a second polarity, where the second magnet has an engaged position and a disengaged position. The second magnet, when in the engaged position, generates a magnetic force with the first magnet, where the magnetic force moves the plunger to force the contact into the first state. The second magnet, when in the disengaged position, removes the magnetic force, where removal of the magnetic force moves the plunger to force the contact into the second state.
In another aspect, the disclosure can generally relate to an enclosure. The enclosure can include an enclosure surface having a front side and a back side. The enclosure can also include a control device disposed proximate to the enclosure surface. The control device of the enclosure can have a first portion positioned proximate to the back side of the enclosure surface. The first portion of the control device of the enclosure can include a plunger having a proximal end and a distal end, where the plunger has a first position toward the enclosure surface and a second position away from the enclosure surface, and where the proximal end is adjacent to the enclosure surface. The first portion of the control device of the enclosure can also include a first magnet having a first polarity and disposed at the proximal end of the plunger. The first portion of the control device of the enclosure can further include at least one contact in communication with the distal end of the plunger, where the at least one contact has a first state and a second state. The control device of the enclosure can also have a second portion positioned proximate to a front side of the enclosure surface. The second portion of the control device of the enclosure can include a second magnet having a second polarity, where the second magnet has an engaged position and a disengaged position. The second magnet, when in the engaged position, moves the plunger to force the contact into the first state. The second magnet, when in the disengaged position, moves the plunger to force the contact into the second state.
In yet another aspect, the disclosure can generally relate to a method for changing a state of an electrical device disposed within an enclosure. The method can include moving a first magnet located outside the enclosure from a first position to a second position, where the first magnet has a first polarity in the second position. The method can also include moving, using a magnetic field generated by the first polarity of the first magnet in the second position, a second magnet having a second polarity from a third position to a fourth position, where the second magnet is located inside the enclosure proximate to the enclosure surface. The method can further include changing, based on moving the second magnet to the fourth position, the state of the electrical device from a first state to a second state.
These and other aspects, objects, features, and embodiments will be apparent from the following description and the appended claims.
The drawings illustrate only example embodiments of magnetic control devices for enclosures and are therefore not to be considered limiting of its scope, as magnetic control devices for enclosures may admit to other equally effective embodiments. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or positionings may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements.
The example embodiments discussed herein are directed to systems, apparatuses, and methods of magnetic control for a device in an explosion-proof enclosure. While the example embodiments discussed herein are with reference to explosion-proof enclosures, other types of non-explosion-proof enclosures (e.g., junction boxes, control panels, lighting panels, motor control centers, switchgear cabinets, relay cabinets) or any other type of enclosure (e.g., hazardous enclosure) may be used in conjunction with example embodiments of fastening devices. As used herein, an explosion-proof enclosure can be an enclosure that is suitable for potentially explosive environments.
As used herein, the cover and the body of an enclosure can be referred to as enclosure portions (e.g., top enclosure portion, bottom enclosure portion). Further, while example magnetic control devices are shown in the accompanying figures as being mechanically coupled to, or located proximate to, the cover of an enclosure, example fastening devices can, additionally or alternatively, be mechanically coupled to, or located proximate to, any other surface of the enclosure.
In one or more example embodiments, an explosion-proof enclosure (also sometimes called a flame-proof enclosure or a hazardous location enclosure) is an enclosure that is configured to contain an explosion that originates inside the enclosure. Further, the explosion-proof enclosure is configured to allow gases from inside the enclosure to escape across joints of the enclosure and cool as the gases exit the explosion-proof enclosure. The joints are also known as flame paths and exist where two surfaces meet and provide an uninterrupted path, from inside the explosion-proof enclosure toward the outside of the explosion-proof enclosure, along which one or more gases may travel. A joint may be a mating of any two or more surfaces. Each surface may be any type of surface, including but not limited to a flat surface, a threaded surface, a rabbet surface, and a serrated surface.
In one or more example embodiments, an explosion-proof enclosure is subject to meeting certain standards and/or requirements. For example, NEMA sets standards with which an enclosure must comply in order to qualify as an explosion-proof enclosure. Specifically, NEMA Type 7, Type 8, Type 9, and Type 10 enclosures set standards with which an explosion-proof enclosure within a hazardous location must comply. For example, a NEMA Type 7 standard applies to enclosures constructed for indoor use in certain hazardous locations. Hazardous locations may be defined by one or more of a number of authorities, including but not limited to the National Electric Code (e.g., Class I, Division 1) and Underwriters' Laboratories, Inc. (UL) (e.g., UL 1203). For example, a Class I hazardous area under the National Electric Code is an area in which flammable gases or vapors may be present in the air in sufficient quantities to be explosive.
As a specific example, NEMA standards for an explosion-proof enclosure of a certain size (e.g., 100 cm3) or range of sizes may require that in a Group B, Division 1 area, any flame path of an explosion-proof enclosure must be at least 1 inch long (continuous and without interruption), and the gap between the surfaces cannot exceed 0.0015 inches. Standards created and maintained by NEMA may be found at www.nema.org/stds and are hereby incorporated by reference.
A user as described herein may be any person that is involved with installation and/or maintenance of enclosures and/or devices within enclosures. Examples of a user may include, but are not limited to, a company representative, an electrician, an engineer, a mechanic, an operator, a consultant, a contractor, and a manufacturer's representative.
Magnets described herein are a material or object that creates a magnetic field. The magnetic field can either repel or attract another magnet, depending on how the polarity of the two magnets are oriented with respect to each other. The magnet can be a permanent magnet, an electromagnet, a rare-earth magnet, a nano-structured magnet, a single-molecule magnet, and/or any other type of magnet that can be used with the example control devices described herein. The strength of the magnetic field can be dictated by one or more of a number of factors, including but not limited to the size of the magnet, the temperature at which the magnet is exposed, and the material of the magnet. The strength of the magnetic field of each magnet can vary and can be set based on one or more of a number of factors, including but not limited to the distance between magnets, interference of the magnetic field by the enclosure surface, and forces (e.g., gravity, friction, resilient devices) that must be overcome.
Example magnetic control devices described herein can be used to change the state of an electrical device. Examples of an electrical device can include, but are not limited to, a VFD (defined below), a motor, a relay, a breaker, a switch, and a sensing device. The electrical device can be positioned inside of or outside of the enclosure. In any case, the electrical device is electrically coupled to a contact of the example control devices. The state of an electrical device can be one or more of a number of operating states, including but not limited to “on”, “off”, “slower”, “faster”, “up”, “down”, “left”, “right”, “open”, and “close”.
Example embodiments of magnetic control devices will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of magnetic control devices are shown. Magnetic control devices may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of magnetic control devices to those of ordinary skill in the art. Like, but not necessarily the same, elements (also sometimes called components) in the various figures are denoted by like reference numerals for consistency. Terms such as “first,” “second,” “distal,” “proximal,” “front,” and “back” are used merely to distinguish one component (or part of a component) from another. Such terms are not meant to denote a preference or a particular orientation.
Referring to
In one or more embodiments, a fastening device 118 may be one or more of a number of fastening devices, including but not limited to a bolt (which may be coupled with a nut), a screw (which may be coupled with a nut), and a clamp. In addition, one or more hinges 116 can be secured to one side of the enclosure cover 102 and a corresponding side of the enclosure body 124 so that, when all of the fastening devices 118 are removed, the enclosure cover 102 may swing outward (i.e., to an open position) from the enclosure body 124 using the one or more hinges 116. In one or more exemplary embodiments, there are no hinges, and the enclosure cover 102 is separated from the enclosure body 124 when all of the fastening devices 118 are removed.
The enclosure cover 102 and the enclosure body 124 may be made of any suitable material, including metal (e.g., alloy, stainless steel), plastic, some other material, or any combination thereof. The enclosure cover 102 and the enclosure body 124 may be made of the same material or different materials. In one or more embodiments, on the end of the enclosure body 124 opposite the enclosure cover 102, one or more mounting brackets 120 are affixed to the exterior of the enclosure body 124 to facilitate mounting the enclosure 100. Using the mounting brackets 120, the enclosure 100 may be mounted to one or more of a number of surfaces and/or elements, including but not limited to a wall, a control cabinet, a cement block, an I-beam, and a U-bracket.
The enclosure cover 102 may include one or more features that allow for user interaction while the enclosure 100 is sealed in the closed position. As shown in
In one or more embodiments, the enclosure cover 102 may also include a switch handle 112 that allows a user to operate a switch 208 located inside the explosion-proof enclosure 100 while the explosion-proof enclosure 100 is closed. Those skilled in the art will appreciate that the switch handle 112 may be used for any type of switch. Each position (e.g., OFF, ON, HOLD, RESET) of the switch may be indicated by a switch position indicator 114 positioned adjacent to the switch handle 112 on the outer surface of the enclosure cover 102. The switch 208 associated with the switch handle 112 and the switch position indicator 114 may be used to electrically and/or mechanically isolate, and/or change the mode of operation of, one or more components inside or associated with the explosion-proof enclosure 100. For example, the switch handle 112 may point to “OFF” on the switch position indicator 114 when a disconnect switch 208 located inside the explosion-proof enclosure 100 is disengaged. In such a case, all equipment located inside the explosion-proof enclosure 100, as well as the equipment (e.g., a motor) controlled by the equipment located inside the explosion-proof enclosure 100, may be without power.
The explosion-proof enclosure 100 of
In one or more embodiments, as shown in
In one or more embodiments, a VFD 206 is affixed to the mounting plate 202 inside the explosion-proof enclosure 100. The VFD 206 may include any components used to drive a motor and/or other device using variable control signals for controlled starts, stops, and/or operations of the motor and/or other devices. Examples of components of a VFD include, but are not limited to, discrete relays, a programmable logic controller (PLC), a programmable logic relay (PLR), an uninterruptible power supply (UPS), and a distributed control system (DSC). In one or more exemplary embodiments, one or more components of the VFD may replace the VFD. For example, the VFD may be substituted by one or more PLCs, one or more PLRs, one or more UPSs, one or more DCSs, and/or other heat-generating components.
In one or more embodiments, a switch 208 is affixed to the mounting plate 202 inside the explosion-proof enclosure 100. The switch 208 may be configured to electrically and/or mechanically isolate, and/or change the mode of operation of, one or more components located inside the explosion-proof enclosure 100 and/or one or more components located outside the explosion-proof enclosure 100. The switch 208 may be any type of switch, including but not limited to a disconnect switch, a test switch, a reset switch, an indicator switch, and a relay switch. For example, the switch 208 may be a disconnect switch that is used to cut off power to all components in the explosion-proof enclosure 100 and all devices located outside the explosion-proof enclosure 100 that are controlled by the components inside the explosion-proof enclosure 100. As another example, the switch 208 may be a bypass switch that is used to deactivate a protection scheme (e.g., a relay) or some other particular component or group of components located inside the explosion-proof enclosure 100.
The switch 208 may further be configured to receive, through mechanical and/or electrical means, a directive to change states (e.g., open, closed, hold) from a component located on the enclosure cover. For example, if the enclosure cover includes a switch handle, as shown in
In one or more embodiments, one or more relays (e.g., relay 212) are affixed to the mounting plate 202 inside the explosion-proof enclosure 100. A relay 212 is a device that may be configured to control one or more operations of one or more components located in, or associated with, the explosion-proof enclosure 100. Specifically, a relay 212 may, through one or more relay contacts, allow electrical current to flow and/or stop electrical current from flowing to one or more components in the enclosure 100 based on whether a coil of the relay 212 is energized or not. For example, if the coil of the relay 212 is energized, then a contact on the relay may be closed to allow current to flow to energize a motor.
The relay 212 may be activated based on a timer, a current, a voltage, some other suitable activation method, or any combination thereof. The relay 212 may also be configured to emit a signal when a condition has occurred. For example, the relay 212 may flash a red light (e.g., indicating light 108) to indicate that the VFD 206 is in an alarm state. In such a case, wiring (not shown) can be run between a back side of an indicating light (e.g., back side 271 of indicating light 106, back side 273 of indicating light 108) and the relay 212. In such a case, the indicting light (e.g., indicating light 106, indicating light 108) creates a flame path with the wall of the aperture in the enclosure cover 102 through which the indicating light extends.
In one or more embodiments, wiring terminals 214 are affixed to the mounting plate 202 inside the explosion-proof enclosure 100. Wiring terminals 214 are a series of terminals where one terminal is electrically connected to at least one other terminal in the series of terminals while remaining electrically isolated from the remaining terminals in the series of terminals. In other words, two or more terminals among the series of terminals act as a junction point where multiple wires may be electrically connected through the joined terminals.
In one or more embodiments, one or more entry holes 216 may extend through one or more sides (e.g., bottom) of the enclosure body 124. Each entry hole 216 may be configured to allow cables and/or wiring for power, control, and/or communications to pass through from outside the explosion-proof enclosure 100 to one or more components inside the explosion-proof enclosure 100. An entry hole 216 may be joined with a conduit and coupling from outside the explosion-proof enclosure 100 to protect the cables and/or wiring received by the entry hole 216 and to help maintain the integrity of the explosion-proof enclosure 100 through the entry hole 216.
In certain example embodiments, a porous media assembly is mechanically coupled to one or more entry holes 216 that traverse a wall in the enclosure cover 102 and/or the enclosure body 124. In any case, the conduit, porous media assembly, or any other device that traverses an entry hole 216 creates a flame path between the conduit, porous media assembly, or any other device and the wall of the entry hole 216.
As another example, along other portions of the outer perimeter of the enclosure cover 300 are disposed a number of (in this case, 8) smaller fastening device apertures 374 that traverse the enclosure cover 300. As yet another example, disposed in a middle portion of the enclosure cover 300 are a number of (in this case, 16) large control device apertures 370. These control device apertures 370 can be used for one or more switches, one or more pushbuttons, one or more indicating lights, and/or any of a number of other control devices that allow a user to communicate, from outside the enclosure, with one or more devices located inside the enclosure.
Each control device aperture 370 shown in the enclosure cover 300 creates a flame path with the control device that traverses therethrough. Similarly, each fastening device aperture 372 and fastening device aperture 374 creates a flame path with the fastening device (e.g., bolt, screw) that traverses therethrough. In some cases, along the outer perimeter of the back surface 303 of the enclosure cover 300 is a channel 333 for receiving a sealing member (e.g., a gasket, an o-ring). The channel 333 is shallow and does not traverse the enclosure cover 300 to the front surface 302. As a result, the channel 333 does not form a flame path.
As a result of the vast distribution of flame paths along the enclosure cover 300, the thickness of the enclosure cover 300 is maximized and is substantially uniform along the enclosure cover 300. In other words, the thickness between the front (outside) surface 302 and the back (inside) surface 303 of the enclosure cover 300 is substantially uniform along the length and width of the enclosure cover 300 This uniform thickness results in higher costs in manufacturing the enclosure cover 300 because of the larger amount of material required.
By contrast, using example magnetic control devices described herein, many of the apertures (particularly, the control device apertures) can be eliminated.
As with the enclosure cover 300 of
Also, as shown for the enclosure cover 300 of
Unlike the enclosure cover 300 of
In addition, because there are no flame paths through the middle portion of the enclosure cover 400, less material is needed in the middle portion. Thus, as shown in
Referring to
In certain example embodiments, the control device 510 includes a first portion 530 and a second portion 550. The first portion 530 of the control device 510 can include a plunger 520, a magnet 512, and at least one contact 570. The second portion 550 can include a magnet 552. The first portion 530 of the control device 510 can be positioned proximate to (including affixed to or mechanically coupled to) the back side 404 of the enclosure surface 400 of the enclosure. The second portion 550 of the control device 510 can be positioned proximate to (including affixed to or mechanically coupled to) the front side 402 of the enclosure surface 400.
In certain example embodiments, one or more components (e.g., the plunger 520, the magnet 512) of the first portion 530 are positioned within a housing 535. The housing 535 can include a cavity 539 inside of which these one or more components of the first portion 530 can move within a range of motion. For example, the cavity 539 can allow for the plunger 520, the magnet 512, and the at least one contact 570 to move within a range of motion.
The housing 535 can be mechanically coupled to the back side 404 of the enclosure surface 400. In such a case, the back side 404 of the enclosure surface 400 can include one or more receiving features for receiving the housing 535. For example, as shown in
In certain example embodiments, the plunger 520 of the first portion 530 has a proximal end (positioned adjacent to the back side 404 of the enclosure surface 400) and a distal end (positioned furthest away from the back side 404 of the enclosure surface 400). As discussed above, the plunger 520 can move within a range of motion provided by the cavity 539 of the housing 535. For example, in a first position, the plunger 520 can be positioned within the cavity 539 toward the enclosure surface 400, where the plunger 520 can be positioned within the cavity 539 away from the enclosure surface 400 in a second position.
As described herein, the distal end of the plunger 520 can be any portion (e.g., middle, far end) of the plunger 520 that is not the proximal end of the plunger 520. The distal end of the plunger 520 can include one or more of a number of features. For example, the distal end of the plunger 520 can include at least one feature that mechanically couples the plunger 520 to one or more contacts 570. In this case, the distal end of the plunger 520 includes a pair of forked sides 523 that extend beyond the outer perimeter of the main body 521 of the plunger 520. Within each forked side 523 is disposed a contact arm 518 (described below), which allows the contact arm 518 to move with the plunger 520 within the cavity 539 of the housing 535.
As another example, the plunger 520 can include at least one feature that prevents the plunger 520 from continuing movement within the cavity 539 of the housing 535. In this case, the distal end of the plunger 520 can include a central member 522 the extends below the forked sides 523 and the contact arms 518. In such a case, the central member 522 prevents the plunger 520 from moving further downward once the plunger 520 is in the second position within the cavity 539 of the housing 535. In other words, the central member 522 contacts a stop 532 within the cavity 539 when the plunger 520 is in the second position. Similarly, the forked sides 523 can be used to prevent the plunger 520 from moving further upward once the plunger 520 is in the first position within the cavity 539 of the housing 535.
In certain example embodiments, the magnet 512 of the first portion 530 of the control device 510 has a polarity. For example, the top end of the magnet 512 can have a polarity. In such a case, the bottom end of the magnet 512 can have another polarity that is opposite the polarity of the top end of the magnet 512. The magnet 512 can be disposed at the proximal end of the plunger 520. In such a case, the magnet 512 can be mechanically coupled to the proximal end of the plunger 520 using one or more of a number of fastening mechanisms, including but not limited to magnetic force, mating threads, epoxy, soldering, welding, snap fittings, compression fitting, slots, tabs, and fastening devices (e.g., screws, bolts).
In certain example embodiments, the magnet 512 and the plunger 520 are the same component, so that the plunger 520 is a magnet with at least one polarity at the distal end. Otherwise, the magnet 512 and the plunger 520 are separate components of the first portion 530 of the control device 510. In any case, the magnet 512 and the plunger 520 can move together between the first position and the second position of the plunger 520 within the cavity 539 of the housing 535. In such a case, the magnet 512 is positioned closest to the enclosure surface 400 when the plunger 520 is in the first position, and the magnet 512 is positioned furthest away from the enclosure surface 400 when the plunger 520 is in the second position.
Each of the one or more contacts 570 can include a contact arm 518 and a contact pad 513. The contact arms 518, described briefly above, can provide a structural (and in some cases electrical) link for the contact pads 513 so that the contact pads 513 move in conjunction with the plunger 520. Thus, each contact 570 is in communication with the distal end of the plunger 520. In other words, as the plunger 520 (and, consequently, the magnet 512) are in the first position, the contact pads are positioned toward the top of the cavity 539 of the housing 535. Similarly, as the plunger 520 (and, consequently, the magnet 512) are in the second position, the contact pads are positioned toward the bottom of the cavity 539 of the housing 535.
In certain example embodiments, each contact 570 has a first state and a second state. The first state of a contact 570 can coincide with the plunger 520 being in the first position, and the second state of a contact 570 can coincide with the plunger 520 being in the second position. The first state of a contact 570 can be an open position (in which the contact is open, preventing current from flowing therethrough) or a closed position (in which the contact is closed, allowing current from flowing therethrough). The contact arm 518 can be made of an electrically conductive material. In such a case, the contact arm 518 can provide electrical continuity within a contact 570 and/or between contacts 570.
The second state of a contact 570 can be the opposite of the first state of the contact 570. In other words, if the first state of a contact 570 closes the contact 570 (puts the contact 570 in a closed position), then the second state of the contact 570 opens the contact 570. Conversely, if the first state of a contact 570 opens the contact 570 (puts the contact 570 in an open position), then the second state of the contact 570 closes the contact 570. The change in the state of a contact 570 can be used to control the operation (e.g., change the state) of one or more electrical devices.
If there is more than one contact 570, the first state of one contact 570 can be the same as, or different than, the first state of another contact 570. Whether the first state of a contact 570 is open or closed can depend on one or more of a number of factors, including but not limited to the configuration of the cavity 539, the shape of the contact arm 518, and the position along the distal end of the plunger 520 where the contact arm 518 is attached. In certain example embodiments, a user can change the first state of a contact 570 from open to closed, or from closed to open.
Optionally, the first portion 530 of the control device 510 can include a resilient device 529 (e.g., a spring). The resilient device 529 can be used to put the plunger 520 (and, thus, the magnet 512) in a default position within the cavity 535 of the housing 530. The default position of the plunger 520 can be the first position or the second position, depending on where the resilient device 529 is placed relative to the plunger 520 within the cavity 535 of the housing 530. In such a case, the plunger 520 remains in the default position unless a force sufficient to overcome the force of the resilient device 529 is applied in a direction opposite the direction of the force applied by the resilient device 529.
For example, a magnetic force generated between the magnet 512 and the magnet 552 (e.g., when the polarities of magnet 512 and magnet 552 attract each other) can be applied in opposition to the force applied by the resilient device 529 and can have a magnitude greater than the force applied by the resilient device 529 to force the plunger 520 from the default position to the other position. When the magnetic force opposing the resilient device 529 is removed (e.g., when the polarities of magnet 512 and magnet 552 oppose each other), the plunger 520 returns to the default position from the other position. In certain example embodiments, regardless of whether there is a resilient device 529, the magnetic force must overcome one or more other forces, including but not limited to gravity and friction between the plunger 520 and the walls of the cavity 535.
For example, as shown in
To make the second position the default position for the plunger 520, the resilient device 529 can be disposed over (e.g., wound around) the magnet 512. The outer perimeter of the magnet 512 (or the proximal end of the plunger 520 if the magnet 512 is integrated as part of the plunger 520) can be less than the outer perimeter of the proximal end of the plunger 520 (or the distal end of the plunger 520) so that the resilient device 529 can be disposed over the magnet 512 (or the proximal end of the plunger 520) and sit atop a lip formed by the proximal end of the plunger 520 (or where the distal end of the plunger 520 meets the proximal end of the plunger 520). In such a case, the outer perimeter of the resilient device 529 can be substantially the same as the proximal end of the plunger 520 (or the distal end of the plunger 520).
To make the first position the default position for the plunger 520, the resilient device 529 can be disposed over some or all of the distal end of the plunger 520. In addition, one or more features (e.g., lips, notches, recesses) can be disposed in the walls of the cavity 535 to allow the resilient device 529 to apply an upward (toward the enclosure surface 400) force on the plunger 520. In any case, the force required to overcome the force of the resilient device 529 (e.g., compress the resilient device 529) and move the plunger 520 from the default position to the other position within the cavity 535 of the housing 530 is less than the magnetic force generated between the magnet 512 and the magnet 552.
The magnet 552 of the second portion 550 of the control device 510 can have a polarity. For example, the top end of the magnet 552 can have a polarity. In such a case, the bottom end of the magnet 552 can have another polarity that is opposite the polarity of the top end of the magnet 552. The magnet 552 can be free-standing, having no other features and being the only component of the second portion 550 of the control device 510. Alternatively, the magnet 552 can include one or more features. For example, as shown in
In such a case, the handling feature 554 can be mechanically coupled to the magnet 552 using one or more of a number of coupling methods, including but not limited to mating threads, epoxy, soldering, welding, snap fittings, compression fitting, slots, tabs, and fastening devices (e.g., screws, bolts). In certain example embodiments, the mechanical coupling between the handling feature 554 and the magnet 552 is secure enough to be maintained when moving the magnet 552 in opposition to the magnetic force between the magnet 552 and the magnet 512.
An optional component of the second portion 550 of the control device 510 is a recessed area (not shown) and/or a collar (not shown) disposed on the front side 402 of the enclosure surface 400. Such component(s) can be called a receiving feature. The receiving feature can be shaped and/or sized to receive the magnet 512. The receiving feature can be used to properly position the magnet 552 relative to the position of the magnet 512 on the back side 404 of the enclosure surface 400. Any such components that may be part of the second portion 550 do not traverse the entire thickness of the enclosure surface 400, and so no flame path is created by the existence of such components of the second portion 550. Other components, features, and/or configurations of the second portion 550 can be used. An example of such other components, features, and configurations are described below with respect to
When the polarity of the magnet 512 relative to the magnet 552 does not change, the magnet 552 can have an engaged position and a disengaged engaged position. When the polarity of the portion of the magnet 552 positioned adjacent to, or in contact with, the front side 402 of the enclosure surface 400 opposes the polarity of the portion of the magnet 512 positioned adjacent to, or in contact with, the back side 404 of the enclosure surface 400, a magnetic force is created between the magnet 512 and the magnet 552. This magnetic force creates an attraction between the magnet 512 and the magnet 552. In such a case, the magnet 552 is in the engaged position.
When the polarity of the portion of the magnet 552 positioned adjacent to, or in contact with, the front side 402 of the enclosure surface 400 is the same as the polarity of the portion of the magnet 512 positioned adjacent to, or in contact with, the back side 404 of the enclosure surface 400, a magnetic force is created between the magnet 512 and the magnet 552. This magnetic force repels the magnet 512 from the magnet 552. In such a case, the magnet 552 is in the disengaged position.
Depending on, at least, the orientation of each contact 570 relative to the plunger 520 and the position of the plunger 520 when the magnet 552 is in the engaged position, when the magnet 552 is in the engaged position, the contact 570 can be in the open position or in the closed position. Conversely, when the magnet 552 is in the disengaged position, the contact 570 is put into the opposite position (i.e., the closed position or the open position) as the position of the contact 570 when the magnet 552 is in the engaged position
Similarly, when the magnet 552 is put in the engaged position, the plunger 520 can be put in the first position or the second position, where such position is not the default position. Conversely, when the magnet 552 is put in the disengaged position, the plunger 520 can be put in the second position or the first position, where such position is the default position.
To move the magnet 552 between the engaged position and the disengaged position, the magnet 552 can be subjected to one or more movements, depending on the components, features, and configurations of the second portion 550 of the control device 510. For example, as shown in
As another example, the magnet 552, having one polarity on one side and an opposite polarity on the other side, can be flipped over and held in place against (or in proximity to) the front side 402 of the enclosure surface 400. In such cases, where one or more receiving features are disposed on the front side 402 of the enclosure surface 400, a tool (e.g., a release paddle, a pry bar) can be used to overcome the attractive magnetic force between the magnet 512 and the magnet 552 to allow the magnet 552 to be flipped from the engaged position to the disengaged position.
The enclosure surface 400 and the control device 610 of
The resilient device 629 is now part of the second portion 650 of the control device 610 rather than the first portion 630, as in
In certain example embodiments, the purpose of the resilient device 629 is to maintain the pushbutton assembly 649 in an unpushed state (a default state or default position for the second portion 650) absent an opposing force that is strong enough to overcome the upward force imposed by the resilient device 629. If a sufficient downward force is applied to the pushbutton 658, where such downward force overcomes, at least, the upward force of the resilient device 629, then the pushbutton assembly is in a pushed state.
The pushbutton assembly 649 can be mechanically coupled to the second magnet 652. For example, as shown in
In this case, the polarity of the magnet 652 remains fixed (i.e., the magnet 652 cannot be flipped to expose the opposite polarity to the magnet 612). Thus, the magnetic force between the magnet 612 and the magnet 652 is always attractive or always repellent. For the configuration shown in
When the pushbutton assembly 649 is in the pressed state, then the magnetic force between the magnet 652 and the magnet 612 is strong enough to draw the plunger 620 upward into the first position. Likewise, when the pushbutton assembly 649 is released to the unpushed state, then the force of gravity returns the plunger 620 to the default position. In certain example embodiments, an additional resilient device can be included in the first portion 630 of the control device 610, as described above with respect to the control device 510 of
Alternatively, the polarities of the magnet 612 and the magnet 652 can be the same (repel other). In such a case, another resilient device can be used with the first portion 630 of the control device 610, as described above with respect to the control device 510 of
The pushbutton assembly 649 can include one or more of a number of components. For example, in this case, the pushbutton assembly 649 can include a transition component positioned between the pushbutton 658 and the bridge 654. All of these elements can be disposed within a cavity of the pushbutton housing 655, which can be mechanically coupled to a coupling member 657. The pushbutton housing 655 can be mechanically coupled to the coupling member 657 using one or more of a number of coupling methods, including but not limited to mating threads (as shown in
The contacts 670 of the first portion 630 of the control device 610 are configured so that the contact 670 shown on the right side of
Referring now to
In certain example embodiments, the side of the magnet 552 facing the front side 402 of the enclosure surface 400 has a polarity and creates a magnetic field. The first position of the magnet 552 can be proximate to (or in contact with) the front side 402 of the enclosure surface 400, while the second position can be further away from the front side 402 of the enclosure surface 400. Alternatively, the first position of the magnet 552 can be removed from the front side 402 of the enclosure surface 400, while the second position can be proximate to (or in contact with) the front side 402 of the enclosure surface 400.
In step 704, the magnet 512 is moved from a third position to a fourth position. The magnet 512 can be moved using the magnetic field generated by the polarity of the magnet 552 while the magnet 552 is in the second position. In certain example embodiments, the magnet 512 is located inside the enclosure 500 proximate to the back side 404 of the enclosure surface 400. The magnet 512 can be part of a first portion 530 of the control device 510. The side of the magnet 512 facing the enclosure surface 400 can have a polarity that is the same as, or opposite of, the polarity of the magnet 552.
The third position of the magnet 512 (described as the first position with respect to
In step 706, the state of the electrical device can be changed from a first state to a second state. A state of the electrical device can be any of a number of operating states, including but not limited to “on”, “off”, “slower”, and “faster”. The state of the electrical device can be changed based on moving the magnet 512 to the fourth position. In doing so, a contact 570 of the first portion 530 of the control device 510, through the plunger 520, changes from an open state to a closed state or from a closed state to an open state. After step 706 is complete, the process can proceed to the END step.
Alternatively, once step 706 is complete, other steps can be performed. For example, magnet 552 can be returned to the first position. The magnet 552 can return to the first position when a user removes the force used to move the magnet 552 to the second position. Alternatively, the magnet 552 can return to the first position by applying a new force, directly or indirectly, by the user to the magnet 552.
When the magnet 552 is returned to the first position, the magnet 512 is moved back to the third position from the fourth position. The magnet 512 can be moved to the fourth position using the magnetic field created by the magnet 552. Specifically, the attraction or repulsion of the magnet 512 from the magnet 552 can be based on the opposite or same polarity, respectively, of the magnet 552 and the magnet 512. When the magnet 512 is moved back to the fourth position, changing, the electrical device is changed to a different state. In certain example embodiments, the electrical device is changed from the second state back to the first state. Alternatively, the electrical device can be changed from the second state to some other state.
In certain example embodiments, the magnetic control device described herein can be used to control one or more electrical devices located inside an enclosure without requiring an aperture that traverses a surface of the enclosure. In such a case, when the enclosure is used in potentially explosive environments, no flame path is created as a result of the magnetic control device. As a result, the enclosure can meet one or more standards and/or regulations with which such an enclosure must comply.
Using example magnetic control devices described herein saves on material costs by allowing for smaller thicknesses of an enclosure surface while allowing the enclosure to maintain its structural and mechanical integrity. Again, because there are no flame paths created by the magnetic control devices described herein, the use of thinner enclosure surfaces allows the enclosure to meet one or more standards and/or regulations with which such an enclosure must comply.
Although embodiments described herein are made with reference to example embodiments, it should be appreciated by those skilled in the art that various modifications are well within the scope and spirit of this disclosure. Those skilled in the art will appreciate that the example embodiments described herein are not limited to any specifically discussed application and that the embodiments described herein are illustrative and not restrictive. From the description of the example embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments using the present disclosure will suggest themselves to practitioners of the art. Therefore, the scope of the example embodiments is not limited herein.
