Patent Application
20070159756
This invention relates generally to devices that control voltage spikes in electrical power, electronic devices that include thermal cutoffs, and methods of improving such devices to enhance safety.
Power surges and voltage spike occur from time to time in power distribution grids, due to, for example, large loads coming off line, power generators being started, switchgear being opened or closed, or the like. Voltage spikes often do not last for very long, but, nevertheless, can cause damage to certain types of electronic devices such as computers, entertainment equipment, communications equipment, and the like that are particularly susceptible to voltage spikes. Consequently, electronic devices including surge protectors or surge suppressors have been developed to protect vulnerable electronic devices from voltage spikes. Surge suppressors have been developed that either block voltage spikes from reaching the susceptible electronic devices, or that short voltage which exceeds a certain threshold.
Surge suppressors have been developed that have a plug configured to be plugged into a wall outlet, for example, and several output receptacles into which power cords for the vulnerable electronic devices can be plugged. Each plug may have a number of conductors, which may include a power or hot line (line in), a neutral (neutral in), and, in many cases, a ground wire (ground in). In addition, surge suppressors have been developed that have one or more current diverters that are electrically connected to the power and neutral lines. The current diverters may pass little or no current when the voltage between the power and neutral lines is below a threshold, but may pass current, thereby limiting voltage, when the voltage between the power and neutral lines exceeds the threshold. An example of a current diverter that has been used in surge suppressors, is a metal oxide varistor (MOV).
When a voltage spike or surge occurs, with the type of surge suppressor that is described, current passes through the current diverter, and power is dissipated by the current diverter as heat. Short duration voltage spikes may be absorbed by such a surge suppressor repeatedly over an extended time without difficulty. But there is a limit to the amount of power, or duration of a voltage spike that typical current diverters can absorb. As examples, lightning striking a power line may cause a very high voltage, or a loss of neutral fault may cause a sustained high voltage. If a voltage surge lasts for a long time, for example, a current diverter may get hot from the power that is being absorbed. In case this happens, surge suppressors have been developed that have one or more thermal cutoffs located near the current diverters. If the current diverter gets hot, it heats up the thermal cutoff, and the thermal cutoff opens, stopping the flow of current. The opening of the thermal cutoff may stop the flow of current to the current diverter, for example. In some prior art surge suppressors, the opening of the thermal cutoff may interrupt power to the output receptacles as well, protecting the vulnerable electronic device from the same or future voltage spikes. Furthermore, some current diverters may deteriorate over time or with use and one or more thermal cutoffs may provide protection in the event current diverters get hot for other reasons as well. In some prior art surge suppressors, current diverters, thermal cutoffs, or both, were wrapped in kapton or Mylar tape.
Despite all of the protections and benefits of prior art surge suppressors, in certain unusual circumstances, interior parts of surge suppressors have gotten hotter than desired and heat has damaged outer surge suppressor enclosures. In some cases, surge suppressors have burned through the outer enclosure. This has occurred even in surge suppressors in which current diverters were wrapped in kapton or Mylar tape. Such an occurrence may cause damage to other equipment, furniture, furnishings, structures, or the like. Overheating of a surge suppressor may result in a fire, human injury, or even death. Consequently, a need or potential for benefit exists for improvements to surge suppressors which prevent, or reduce the likelihood of, heat from interior components damaging outer enclosures of surge suppressors (e.g., burning through) or damaging items outside the outer enclosure. Needs also exist, or would be beneficial, for such improvements to be inexpensive, conducive to mass production, use available materials and components, be durable and reliable, and not inhibit functionality. Further, needs exist, or would be beneficial, for both surge suppressors having such improvements and methods of improving surge suppressors.
Further, various electronic devices include thermal cutoffs, for instance, configured to open and interrupt power in the event one or more components within the electronic device were to overheat. Certain thermal cutoffs have been used which include a metal body that may be electrically connected to one lead of the thermal cutoff. In the prior art, such thermal cutoffs were typically installed without attention to their orientation. In the event the metal body was electrically connected to the unprotected side of the thermal cutoff, if the metal body were to contact other electrically-conducting materials, electrical current may be able to pass through those materials even if the thermal cutoff was open. In some circumstances, the event that caused the thermal cutoff to open may have caused the body to contact other electrically-conducting materials. Consequently, a need or potential for benefit exists for improvements to such electronic devices that prevent this from happening. Needs or potential for benefit also exists for such improvements to be inexpensive, conducive to mass production, use available materials and components, be durable and reliable, and not inhibit functionality.
Other needs and potential for improvement may be apparent from this disclosure or may be know to those of skill in the art. Particular embodiments of the present invention may partially or completely fulfill one or more of these needs, or may provide other benefits which may or may not be readily apparent. Potential for improvement exists in these and other areas that may be apparent to a person of skill in the art having studied this document.
Embodiments of this invention include methods of improving the safety of electronic devices, such as surge suppressors, and such devices with certain improvements that may enhance their safety under particular circumstances. Specifically, the improvements may reduce the risk of the outer enclosure of an electronic device such as a surge suppressor burning through or being damaged as a result of overheating of internal electrical components. Various improvements in accordance with the present invention include changes to the layout or orientation of electrical components, for instance, so that certain components are at a closer electrical potential to their neighbors, and changes to (or additions of) various electrical components.
Various embodiments of the invention provide as an object or benefit that they partially or fully address one or more of the needs, potential areas for improvement, and functions described herein, for instance. The present invention provides various embodiments that may be safer or may provide a higher level of safety in comparison with various prior art. Specifically, embodiments are provided that reduce the likelihood of an outer enclosure of an electronic device burning through under certain circumstances. Further features and advantages of the invention may be apparent to those skilled in the art.
In certain specific embodiments, the invention provides various methods of improving the safety of a surge suppressor configured to pass an electrical current to at least one electronic device and to absorb voltage spikes in the electrical current thereby protecting the at least one electronic device from the voltage spikes. Such methods may include one or more of several steps. One such step is a step of revising a layout of the electrical components so that a plurality of MOVs are at a closer electrical potential to adjacent electrical components. Another example is the step of changing the orientation of at least one thermal cutoff so that the exterior of each thermal cutoff is electrically connected to the protected side of the thermal cutoff.
In some embodiments, MOVs are oriented so that a side of the MOVs is adjacent to a thermal cutoff that is normally at substantially the same electrical potential as the thermal cutoff. Further, some embodiments of the invention include the step of replacing at least one thermal cutoff having an electrically conducting exterior with a thermal cutoff having a non-conducting exterior. Even further, some embodiments of the invention include a step of advertising that the surge suppressor is safer. Further still, some embodiments include the step of installing a second thermal cutoff in series with a first thermal cutoff so that if either thermal cutoff opens, the electrical current will be interrupted. In some embodiments, the method further includes the step of repositioning a thermal cutoff, an MOV, or both, for better thermal contact between the MOV and the thermal cutoff to provide quicker operation of the thermal cutoff.
The invention further provides, in another specific embodiment, an electronic device having electrical components including a plurality of thermal cutoffs, each with a metal exterior, a protected side, and an unprotected side, wherein the exterior of each thermal cutoff is electrically connected to the protected side of the same thermal cutoff. In a number of embodiments, a thermal cutoff is sandwiched between a first current diverter and a second current diverter, which may be located and oriented so that a side is adjacent to the thermal cutoff that is normally at substantially the same electrical potential as the thermal cutoff. Further, in some embodiments, each thermal cutoff is arranged in a block in between at least a first current diverter and a second current diverter.
The electronic device may be a surge suppressor, in some embodiments, that includes an input having a first conductor and a second conductor, an output configured to pass an electrical current, an outer enclosure, and at least one current diverter wired between the first conductor and the second conductor. In some embodiments, the input includes a line-in plug electrically connected to the first conductor and to the second conductor, and the first conductor is configured to connect to line power and the second conductor is configured to connect to neutral. In some embodiments, the output includes a plurality of output receptacles, and the thermal cutoff is wired so that when it opens, electrical current to the output receptacles is interrupted. Such a surge suppressor may be configured to pass the electrical current from the input to the output and to at least one electronic device electrically connected to the output and to absorb voltage spikes in the electrical current thereby protecting the at least one electronic device from the voltage spikes, for example.
In yet another specific embodiment, the invention further provides a surge suppressor that includes a thermal cutoff in between and adjacent to two MOVs that are arranged so that the sides that are normally at substantially the same electrical potential as the thermal cutoff are adjacent to the thermal cutoff. In some such embodiments, there are a plurality of thermal cutoffs, and each thermal cutoff is arranged in a block in between two MOVs with the MOVs arranged so that the side that is normally at substantially the same electrical potential as the thermal cutoff in the same block is adjacent to the thermal cutoff. In some embodiments, the other side of the MOVs are electrically connected to a hot line in or a neutral in, and at least a plurality of these blocks may be arranged so that the blocks are adjacent to each other and so that these “other” sides of the MOVs are adjacent to each other. In some embodiments, the thermal cutoff also has a metal exterior that is electrically connected to the protected side of the thermal cutoff.
The figures in this document illustrate various exemplary embodiments of the present invention, wherein like reference numerals represent like elements. Embodiments of the invention may include part or all of the features shown in one of these drawings, or may include features from two or more figures, or features from both the drawings and the specification. Accordingly,
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
This invention includes, in various embodiments, electronic devices that contain electrical components including at least one thermal fuse or thermal cutoff, various improved surge suppressors, and certain methods of making or improving the safety of such devices and surge suppressors. The surge suppressor embodiments may be configured to pass an electrical current to at least one electronic device and to absorb voltage spikes in that electrical current thereby protecting the electronic device from the voltage spikes, for example.
A number of embodiments of the invention include one or more enclosures surrounding certain electrical components, which may serve to prevent electrical contact between electrical components in the event of catastrophic failure or overheating of at least one electrical component. Specifically, enclosures may contain or surround various electrical components including conductors or wires, for example, and may be made of an electrically insulating material, a material with a high melting point, or a material such as fiberglass, with both such properties.
Certain embodiments include an enclosure surrounding a thermal cutoff. Such an enclosure may include a layer of fire-resistant material having electrical insulating properties at least partially surrounding the thermal cutoff, for example. In some embodiments, the enclosure may surround the thermal cutoff separate from other electrical components, for instance. In some embodiments, such an enclosure may surround at least one thermal cutoff and at least one current diverter, and the current diverter may be located adjacent to the thermal cutoff. The thermal cutoff may be located close to, or in between, one or more current diverters for better thermal contact and to provide quicker operation of the thermal cutoff, for example. In other embodiments, enclosures may surround wires or conductors.
Further, in various embodiments, electrical components, such as current diverters, may be arranged so that certain components, or sides of certain components, are at a closer electrical potential to adjacent components or sides thereof. Further, in particular embodiments, the orientation of thermal cutoffs are controlled so that the metal exteriors of thermal cutoffs are electrically connected to the protected side of the thermal cutoffs. Moreover, in different embodiments, thermal cutoffs with non-metal bodies or exteriors may be used. Still further, in some embodiments, one or more additional thermal cutoffs may be installed in series with a first thermal cutoff to provide redundancy and assure that if either thermal cutoff opens, the electrical current will be interrupted. Various combinations of these and other improvements may be found in different embodiments of the invention.
Various embodiments of the invention may have improved safety features. For instance, improvements may provide an additional level of protection in the event a device fails, for example, due to an excessive surge, age, or defects in one or more components. Certain improvements may make such a failure less destructive. In some embodiments, certain improvements may reduce the likelihood that the outer enclosure will burn through, reduce smoke production, reduce the concentration of escaping heat, reduce damage to external components, or the like.
Looking now at particular embodiments illustrated in the figures,
Output 18 may be an output receptacle, for example, for one or more of various electronic devices to plug into that circuit 10 may be configured to protect. Output 18 may include contacts 18a, 18b, and 18c, which may be electrically connected to conductors 19i, 19j, and 19k, which may be hot (line power), neutral, and ground, respectively, for example. Some embodiments of circuit 10 may be hard wired, for example, to the device or devices that such embodiments are configured to protect. As such, these embodiments may omit the output receptacle found in other embodiments of the invention. In some embodiments, an input plug may also be omitted in favor of hard wiring or another type of connection, for instance. Further, some embodiments may not include a ground. Still further, some embodiments may include one or more other electrical components that may connect to ground, such as one or more current diverters, for example.
As mentioned, circuit 10 includes thermal cutoffs 11 and 12 in the embodiment illustrated. As used herein, thermal cutoffs are electrical devices that are normally closed and normally conduct electricity with little or no impedance, but if the thermal cutoff reaches a threshold temperature, such a thermal cutoff will open and substantially stop conducting electricity, at least at normal voltages. With some types of thermal cutoffs (as that term is used herein), once they open, they stay open. As an example, certain types of thermal cutoffs have wax inside. When the wax melts, a spring pushes or pulls electrical contacts apart, interrupting the flow of electricity. Devices with such thermal cutoffs may be discarded in the event a thermal cutoff opens. In other embodiments, thermal cutoffs (as used herein) may be configured to reset (close) either automatically (e.g., after they cool down) or manually (e.g., by pressing a reset button).
Focusing on the example of a thermal cutoff illustrated, and thermal cutoff 11 specifically, thermal cutoff 11 includes lead or side 11a, body or exterior 11b, and lead or side 11c. Thermal cutoff 11 generally includes other components as well, which have been omitted for clarity, but would be familiar to a person of ordinary skill in the art. Body or exterior 11b may be metal, in some embodiments, may be electrically conducting, and may be electrically connected to side 11c. In the embodiment shown in
The embodiment of circuit 10 that is illustrated includes two thermal cutoffs, cutoff 11 and cutoff 12, which are shown wired in series. Thus, if either cutoff 11 or cutoff 12 opens, electrical current through contact 17a and conductor 19a, for example, will be interrupted and prevented from passing through any of the current diverters 13-16 or to output 18 (i.e., through conductor 19i and contact 18a). Some embodiments may have only one thermal cutoff, but having two adds redundancy and may improve safety, other things being equal. With two thermal cutoffs (11 and 12) if one fails to open, or is shorted across, the other thermal cutoff may still open and interrupt the electrical current when warranted. Further, in embodiments that have more than two current diverters, additional thermal cutoffs may be intermingled within the current diverters or placed between them, which may reduce the time that it could take for a thermal cutoff to open if just one current diverter gets hot. Thus, two thermal cutoffs may improve reliability and safety in comparison to embodiments with one thermal cutoff. Other embodiments may have more than two thermal cutoffs, such as, for example, 3, 4, 5, 6, 8, 10, or 12 thermal cutoffs.
Circuit 10 illustrates an example of how thermal cutoffs 11 and 12 may be wired in an electronic device such as a surge suppressor. In other embodiments one or more of these thermal cutoffs 11 and 12 may be at a different location in the circuit. For example, in some embodiments, one or both of thermal cutoffs 11 and 12 may be in the other line, for example, in conductor 19b, connected to contact 17b.
In some embodiments, one or more thermal cutoffs may be in series with one or more of current diverters 13-16, for example, in conductor 19m. In such a configuration, if the thermal cutoff opens, the electrical current through the current diverter (or diverters), for example, current diverter 13, may be interrupted, but the current to output 18, for example, through conductor 19i, may be uninhibited. A surge suppressor with such wiring may continue to pass power after one or more thermal cutoffs are open, but may have lost its ability to absorb voltage spikes. In some embodiments, a user may not be able to tell that such a surge suppressor is no longer performing its intended function. Other such surge suppressors may have indicator lights, or other features, to show whether or not they are still capable of absorbing voltage spikes.
In some embodiments, thermal cutoffs may be installed in the conductor from contact 17a to 18a, but in between current diverters (for example, between current diverters 14 and 15 within conductor 19g). In such a configuration, if the thermal cutoff opens, it will interrupt power to current diverters 15 and 16 and to contact 18, but not to current diverters 13 and 14. A number of alternative embodiments may be apparent to a person of skill in the art. Current diverters 13, 14, 15, and 16, in an example of the invention that is a surge suppressor, may be wired between two conductors, for example, line and neutral, for example, conductors 19g and 19b, and may be configured to absorb voltage spikes between, for example, conductors 19g and 19b. Thus, current diverters 13-16 may reduce or eliminate at least some voltage spikes, for example, at output 18. Each of current diverters 13-16 may be configured to have a high resistance when the voltage across them is less than a threshold voltage. This resistance may be or approach an infinite resistance, for example. However, the resistance of current diverters 13-16 may decrease when the voltage exceeds the threshold voltage, thus allowing a significant amount of current to pass through current diverters 13-16. Such a threshold voltage may be 120 Volts RMS, for example. The resistance of current diverters 13-16 may decrease sharply as the voltage across them exceeds the threshold voltage. Thus, voltage in excess of the threshold voltage may be effectively dumped or diverted through current diverters 13-16. Energy present in voltage spikes may be absorbed by current diverters 13-16 and dissipated as heat. Current diverters may have a large surface area to facilitate dissipation of heat, and may be flat, for example. In different embodiments, current diverters may be flat, but round or rectangular, as examples. Other embodiments may have different shapes.
Current diverters 13-16 may be able to absorb many short transient voltage spikes over a long period of time, but if the voltage across current diverters 13-16 exceeds the threshold voltage fairly continuously for a long time, or if the voltage across current diverters 13-16 exceeds the threshold voltage by too much, or a combination of such conditions, current diverters 13-16 may become hot, and this heat may damage current diverters 13-16, surrounding components, or even external materials. Consequently, thermal cutoffs 11 and 12 are included in circuit 10 and a number of embodiments of the invention to shut off the electrical current in the event heat from current diverters 13-16 becomes excessive. For the sake of safety, it is usually desirable that at least one of thermal cutoffs 11 and 12 opens before enough energy has been absorbed that external materials are damaged.
In the embodiment illustrated, circuit 10 includes four (4) current diverters 13-16. However other embodiments may have different numbers of current diverters. For instance, surge suppressors in accordance with the invention may have 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 20, 24, 30, or more, or another number, of current diverters. In some embodiments, there may be two current diverters for each thermal cutoff, but this is not necessarily true of all embodiments.
In particular embodiments, current diverters 13-16 may be metal oxide varistors (MOVs), Zener diodes, or gas discharge arrestors, as examples. In some embodiments, each current diverter may be made up of a number of small devices or structures that may be connected in series, in parallel, or a combination thereof. In some embodiments of surge suppressors, instead of or in addition to current diverters in parallel with the electronic device (or devices) being powered, an electronic variable resistor is located in series with the electronic device (or devices), and the resistance of this variable resistor is increased when the line voltage exceeds the threshold voltage.
Other embodiments of electronic devices in accordance with the invention may or may not include current diverters such as MOVs, but may include other electrical components and may include thermal cutoffs. In such embodiments, the other electrical components may be a potential source of heat, or there may be some other potential heat source. The thermal cutoffs may be configured to open when a sufficient amount of heat is present, for example, resulting in a particular temperature.
Turning now to
In various embodiments, thermal cutoff 11 may be located in between current diverters 13 and 14 as shown, and thermal cutoff 12 may be located in between current diverters 15 and 16. In the embodiment illustrated, thermal cutoff 11 and current diverters 13 and 14 form a block. In this embodiment, thermal cutoff 12 and current diverters 15 and 16 form another block. Such a blocks may be repeated one or more times in different embodiments of the invention. Thus, different embodiments may have one block, two blocks (as shown) three blocks, four blocks, or 5, 6, 8, or 10 blocks, as examples. Each block may contain at least one thermal cutoff and at least one current diverter. In the embodiment illustrated, each block contains one thermal cutoff and two current diverters, but other embodiments may contain two or more thermal cutoffs in each block, and one, two, three, four, six, eight, ten or more, or a different number of current diverters, for example.
Surge suppressor 20 may include outer enclosure 21. In some embodiments, input 17 may be a plug, and may be located at or extend from outer enclosure 21. In other embodiments, input 17 may be a plug and a cord may extend from enclosure 21 to input 17. Further, in some embodiments, a plurality of output receptacles may be present in enclosure 21. Such output receptacles may form output 28 shown in
Further, various surge suppressors in accordance with the invention may include a number of other components, represented in
Still referring to
In certain embodiments of the invention, including surge suppressor 20, one or more of the current diverters and thermal cutoffs are arranged so that the first sides of the current diverters are adjacent to the thermal cutoffs. In some embodiments, that is the case for all current diverters, or all that are adjacent to thermal cutoffs. In the embodiment illustrated, side 13a of current diverter 13 is adjacent to thermal cutoff 11, side 14aof current diverter 14 is adjacent to thermal cutoff 11, side 15a of current diverter 15 is adjacent to thermal cutoff 12, and side 16aof current diverter 16 is adjacent to thermal cutoff 12. This may reduce the potential for additional current flow should a current diverter contact an adjacent thermal cutoff.
In certain embodiments, various components or groups of components, for example, current diverters 13-16, or the blocks described herein, may be arranged so that the second sides of certain current diverters are adjacent to each other. For example, in surge suppressor 20 shown in
In some embodiments, surge suppressor 20 may include at least one barrier or layer between electrical components, such as barrier 22, barrier 23, barrier 24, barrier 25, or a combination thereof. Barriers 22 and 25 may separate current diverters 13-16 and thermal cutoffs 11 and 12 from other components, within outline 26, for example, within surge suppressor 20, from outer enclosure 21, or both. In particular embodiments, barriers 22 and 25 may each contain a block, as described herein. For instance, as illustrated, barrier 22 contains thermal cutoff 11 and current diverters 13 and 14. In some embodiments, barriers 22 and 25 may be combined into one barrier, which may contain multiple blocks, for example, thermal cutoffs 11 and 12 and current diverters 13-16.
In the embodiment illustrated, barrier 23 contains thermal cutoff 11, and barrier 24 contains thermal cutoff 12. In some embodiments, each of barriers 23 and 24 may contain no other electrical components (e.g., besides wires and conductors), for example, current diverters 13-16 or other components, such as represented by outline 26. In various embodiments, one or more of barriers 22-25 may form an inner enclosure within outer enclosure 21, for example. In some embodiments, various other components, for example, components represented by outline 26, may be located in between the inner enclosure (e.g., one or more of barriers 22-25) and outer enclosure 21, for example. Further, in various embodiments, one or more of barriers 22-25 may form, in whole or in part, a barrier separating the contents of the barrier from other components.
In some embodiments, barrier 22 may form a first barrier, and barrier 23 may form a second barrier, for example. The same could be said of barriers 25 and 24, respectively, in some embodiments. In some embodiments, the first barriers (e.g., barriers 22 and 25) may enclose at least one thermal cutoff and at least one current diverter, and may contain heat produced by the current diverter(s) so that the heat is efficiently transferred to the thermal cutoff, and may also protect the other components (e.g., components represented by outline 26), the outer enclosure 21, and materials beyond, from the heat. The first barriers (e.g., barriers 22 and 25) may also help to prevent the thermal cutoff, current diverter(s), and conductors therein or nearby from making electrical contact with other components or conductors located between the first barrier and the outer enclosure 21. The second barriers (e.g., barriers 23 and 24) may help to prevent the thermal cutoff (e.g., 11 or 12), from making electrical contact with the current diverters (e.g., 13, 14, 15, or 16). In various embodiments, the barriers, layers, and enclosures herein may provide thermal insulation, provide electrical insulation, or both, for instance, between current diverters and various electrical components, the rest of the electrical circuitry, or the outer barrier, as examples.
In various embodiments, one or more of barriers 22-25 may be formed by at least one layer of a material that has electrical insulating properties. Such a material may, for example, not significantly conduct electricity at the voltage normally found between contacts 17a and 17b, for example, at 110, 115, or 120 Volts RMS. In certain embodiments, the material may be fire resistant. In various embodiments, the material of one or more of barriers 22-25 may be self-extinguishing, non-combustible, non-flammable, have a low flammability, or a combination thereof. In various embodiments, the material of one or more of barriers 22-25 may not ignite, burn, release heat, release smoke, melt, or distort, when exposed to heat or certain high temperatures, for example. In some embodiments, the material of one or more of barriers 22-25 may retain its shape, substantially retain its strength, substantially block radiant heat transfer, or a combination thereof, when exposed to heat or certain high temperatures. As an example, in particular embodiments, the material may comprise or consist of fiberglass, for example, fiberglass cloth. In other embodiments, the material may comprise or consist of a polymer or plastic, which may be a thermal plastic or a thermal set plastic, for example. In some embodiments, different materials or numbers of layers, for example, may be used to make different barriers 22-25, or a combination thereof.
In some embodiments, an enclosure or barrier, such as illustrated by outline 26, may surround one or more wires or conductors, for example, to keep them from making electrical contact with other electrical components, to reduce heat transfer, or both, in the event of a destructive failure of the device. Such an enclosure or barrier as represented by outline 26 may be made of a material that has a relatively high melting point, that is an electrical insulator, or both, such as fiberglass cloth, for example. For instance, in some embodiments, one or more wires or conductors may pass through an enclosure or barrier made of tubular fiberglass cloth, which may separate the wires or conductors from nearby electrical components such as current diverters, for example, or from other wires or conductors. In the embodiment illustrated, wires or conductors 19b, 19j, and 19c pass through barrier 26. In other embodiments, each wire or conductor may have its own barrier, or different combinations of wires or conductors may pass through a common barrier or enclosure.
Next we will turn to
In some embodiments, enclosure 43 may be a sleeve or tubular, and in the embodiment illustrated, has a vertical axis (in the orientation shown in
In
In various embodiments, enclosure 52 may or may not extend to or be attached to circuit board 37, for example, at bottom 59. In some embodiments, enclosure 52 may be attached to current diverter 33, another current diverter, enclosure 43, thermal cutoff 31, or a combination thereof, for instance, with adhesive. In other embodiments, enclosure 52 may be held in place with friction, by an outer enclosure, or both. In different embodiments of a surge suppressor or other electronic device, enclosure 52 or an alternative embodiment, may be provided with or without enclosure 43, and vice versa. In some embodiments, enclosures 52 and 43 may be formed in one piece, or from the same piece of material.
As illustrated, in this embodiment, MOVs 63a and 63b are larger than current diverters 63c and 63d. In some embodiments, larger MOVs (e.g., 63a and 63b) may be electrically connected to line and neutral, while smaller MOVs (e.g., 63c and 63d) may be electrically connected to ground and one of line and neutral. But this need not be the case in all embodiments. In certain embodiments of surge suppressor 60, MOVs 63a-63d may be oriented so that the side that is closest to a thermal cutoff is normally at substantially the same electrical potential as the thermal cutoff. In addition, in certain embodiments, the adjacent sides of MOVs 63b and 63c may be of a relatively close or substantially identical electrical potential, in comparison to opposite sides of these MOVs, for example. Further, thermal cutoffs 62a and 62b may be redundant, the second being provided in case the first one fails to open when warranted.
Surge suppressor 70, in this example, includes a plastic barrier 75. Plastic barrier 75 is an example of barriers 22 and 25 shown in
Plastic used for barrier 75 may be selected to be flame-retardant, fire-resistant, to have a high melting point, or a combination thereof, in various embodiments. In some embodiments, barrier 75 may be made of a thermal set plastic, for example. In other embodiments, barrier 75 may be made of flame retardant Kraft paper, phenolic material, or glass, as examples. In some embodiments, barrier 75 may be metal, which may be coated with an electrically insulating material in some embodiments.
The preceding
At this point, we will turn from describing examples of electronic devices, such a surge suppressors, to describing methods in accordance with the invention. However, methods in accordance with the invention may include aspects of the above electronic devices, and vice versa. In certain embodiments, a previous design of an electronic device such as a surge suppressor may be modified or improved, for example, to improve safety in the event internal components such as current diverters become hot, for example, as a result of a large or sustained surge. In other embodiments, an improved or safer electronic device, such as a surge suppressor, may be designed or built from scratch, with certain steps or features in accordance with the invention to improve safety, for example. Accordingly,
Burn through of an outer enclosure of an electronic device such as a surge suppressor may be triggered by a lightning strike causing a very high voltage, or a wiring fault, such as a loss of neutral fault, causing an extended high voltage, as examples. In a surge suppressor, for instance, such an event may result in a current diverter passing more current and energy than it is able to handle. As a result, the current diverter may become hot or overheat. Although thermal cutoffs may be included to interrupt the circuit and terminate the source of heat, in unusual circumstances, prior art technology surge suppressors would not always terminate the source of heat in time to prevent burn through of the outer enclosure. Various embodiments of the invention include steps that may reduce or eliminate this problem.
In some cases, an outer enclosure may burn through because the thermal cutoff (or cutoffs) does not open soon enough. For instance, enough heat may be released to burn through the outer enclosure before a thermal cutoff gets hot enough to open. This may be because heat is directed at the outer enclosure, because not enough heat is directed at the thermal cutoffs, or both. Further, in some cases, initial heat, combustion, or escaping gasses, may cause various conducting components to touch each other, or arc to each other, allowing more current to pass and causing more heat to be produced. Still further, in some cases, one or more components may fail to function as intended, for example, due to a surge or another cause. Various embodiments of the invention involve steps to address these and possibly other modes of failure, and may reduce the likelihood of burn through of the outer enclosure.
However, it should be noted that the present invention will not necessarily eliminate all possibility of burn through of the outer enclosure of a surge suppressor, for example. For instance, lightning strikes may produce such high voltages that arcing will occur between components, no matter how the components are arranged or configured. Even so, a reduction of the likelihood of outer enclosure burn through may provide a substantial benefit, especially provided the cost of the improvement is minimal or not excessive.
In the embodiment illustrated in
In some embodiments, the step of revising the layout of components (step 101) may include, for example, reorienting current diverters such as MOVs in relation to each other. In some embodiments, the step of revising the layout of components (step 101) may include, for example, positioning (or repositioning) current diverters, or blocks of current diverters and one or more thermal cutoffs, for example, so that sides of current diverters that are not normally at substantially the same electrical potential as the thermal cutoffs are adjacent to each other. For instance, positioning sides 14b and 15b of current diverters 14 and 15 shown in
The layout of components may be revised (step 101), for example, so that the components are less likely to make electrical contact with each other in the event one or more of the components overheats or fails, for instance. As an example, such a change in arrangement of components may reduce the likelihood that such electrical contact will occur in the event that one or more MOVs in a surge suppressor overheats as the result of a large or extended high- voltage condition. Preventing this electrical contact may avoid further or more severe failure of the device or electrical components, and may reduce the likelihood that the outer enclosure of the device burns through or the extent to which external materials are damaged or placed in jeopardy.
As used herein, “electrical components”, in the context of step 101 shown in
Conductors may be located away from components or surfaces of components that are normally or likely to be at a significantly different electrical potential, for example, when possible or convenient to do so.
As an example, electrical wires may be located away from MOVs in surge suppressors (or the MOVs may be located away from the electrical wires) so that heat from an overheating MOV will not melt or burn through the insulation on such wires resulting in a short or the formation of an electrical circuit between the wire and the MOV, in some embodiments. An exception in certain embodiments, may be that a wire that is electrically connected to an MOV may be located by that MOV, specifically, in certain embodiments, by the side of the MOV that the electrical wire is electrically connected to.
In the embodiment illustrated, method 100 also includes the step of providing a barrier between electrical components (step 102). As an example, a barrier may improve safety by preventing electrical contact between the two (or more) electrical components in the event of the overheating or catastrophic failure of one of the electrical components or a nearby electrical component. For instance, a barrier may be provided between a current diverter, such as an MOV, and another electrical component to prevent electrical contact in the event the current diverter or MOV overheats. The barrier may be fire resistant, may have electrical insulating properties, or both, in some embodiments. As an example, the barrier may be made of fiberglass.
In some embodiments, the barrier may enclose or substantially enclose at least one electrical component. For instance, the barrier may be tubular and may enclose at least one wire or conductor. An example of this is a barrier represented by outline 26 shown in
Another example of providing a barrier (step 102) involves enclosing a current diverter and a thermal cutoff with insulation. Examples of this step include providing enclosure 22 or 25 (or both) shown in
Certain embodiments include substantially enclosing at least one MOV and at least one thermal cutoff within a fire-resistant barrier having electrical insulating properties forming an inner enclosure within an outer enclosure wherein a plurality of electrical components are located in between the inner enclosure and the outer enclosure. These electrical components that are located in between the inner enclosure and the outer enclosure may be other than, or in addition to, various wires and conductors, in some embodiments.
In many embodiments, a barrier (e.g., of step 102) may be positioned and configured to prevent electrical contact between electrical components in the event of an overheating or failure of one of the components, for example, a current diverter. Further, in a number of embodiments, the enclosure, barrier, or insulation may electrically isolate the components within from other components or conductors outside the enclosure, barrier, or insulation. In various embodiments, the enclosure, barrier, or insulation may be fire resistant, for example, such as fiberglass. Further, in various embodiments, the enclosure, barrier, or insulation may have electrical insulating properties, for instance, as described herein. Fiberglass is also an example of a material that has electrical insulating properties. Still further, in some embodiments, the enclosure, barrier, or insulation may form an inner enclosure within an outer enclosure, and a plurality of electrical components may be located in between the inner enclosure and the outer enclosure. Examples of such electrical components include other components discussed above with reference to outline 26 shown in
In a number of embodiments, the enclosure, barrier, or insulation may also (or instead) help to contain heat from a current diverter, for example, to protect other components, the outer enclosure, or the exterior, to heat the thermal cutoff so that it will open sooner, or a combination thereof.
Certain embodiments of the invention include changes that may reduce the likelihood of detriment resulting from various components making electrical contact with a metal body or exterior of a thermal cutoff. Such changes include, as examples, enclosing a thermal cutoff with insulation (an example of step 102), replacing a thermal cutoff having a metal body with a thermal cutoff having a non-metal body (step 103) and changing the orientation of a thermal cutoff so that the exterior is electrically protected (step 104). Different embodiments of the invention may include one or more of these steps.
Specifically, still referring to
In a number of embodiments, the thermal cutoffs may have a metal body or exterior (e.g., body or exterior 11b and 12b shown in
In various embodiments, the enclosure, barrier, or insulation may be fire resistant, for example, such as fiberglass, which may allow it to remain intact even if a large amount of heat is produced nearby. Further, in some embodiments, the enclosure, barrier, or insulation may form an inner enclosure within an outer enclosure, and a plurality of electrical components may be located in between the inner enclosure and the outer enclosure. In different embodiments, various combinations of barriers or enclosures may be provided.
Certain embodiments of the invention, such as method 100 illustrated, include a step of replacing a thermal cutoff having a metal body with a thermal cutoff having a non-metal body (step 103). In many embodiments, this step will be performed in lieu of step 102, or vice versa. But some embodiments may include both steps 102 and 103, for example, for different thermal cutoffs, or to provide additional protection . Such a non-metal body may reduce the risk of an electrical connection occurring as a result of the thermal cutoff contacting other electrical components or conductors, for example, in the event a nearby components burns up in an explosive manner causing nearby parts to move relative to each other.
Further, a number of embodiments include a step of changing the orientation of at least one thermal cutoff so that the exterior is protected (step 104). For instance, thermal cutoffs may be oriented so that the bodies or exteriors are electrically connected to the protected sides of the thermal cutoffs, for instance, rather than to the unprotected side. Examples of such an orientation are illustrated in
Various embodiments of the invention include installing at least one (or at least one more) redundant thermal cutoff (step 105). For instance, one or more thermal cutoffs may be installed in series, so that if either thermal cutoff opens, the electrical current will be interrupted. In some embodiments, redundant thermal cutoffs may be installed adjacent to different current diverters, for example. In other embodiments, redundant thermal cutoffs may be installed adjacent to the same current diverters. As an example, thermal cutoffs 62a and 62b shown in
A number of embodiments include the step of repositioning a thermal cutoff, a current diverter, or both, for better heat transfer between such components (step 106). This may involve obtaining better thermal contact between at least one current diverter (e.g., MOV) and at least one thermal cutoff, for example, to provide quicker operation of the thermal cutoff. This may happen, for example, in the event the current diverter suddenly starts to produce heat, for instance, in the event of a high or prolonged power surge. Such components may be positioned closer to each other, for example, or may be arranged so that they are parallel (e.g., rather than perpendicular) In some embodiments, thermal cutoffs may be positioned in between more than one current diverter, for instance, sandwiched in between. In some embodiments, heat transfer may be enhanced in other ways such as, for example, adding a heat sink or heat conducting medium, adding heat reflectors, adding enclosures, or the like.
Various methods of improving the safety of electronic devices, such as surge suppressors, for example, include the step of advertising that the product is safer (step 107). Advertising that an electronic device is safer may include mentioning that the product is less likely to cause a fire or cause damage to external materials, or advertising that it is less likely to burn through the outer enclosure or body, for example. Advertising that an electronic device is safer may include mentioning or describing one or more of the improvements described herein. But in other embodiments, a specific description of the improvement or improvements may be omitted. Some embodiments may include, in the advertising, an explanation of the benefits of the improvement, which may be related to safety. Advertising that a product is safer (step 107) may include marking the product, marketing product packaging, mentioning that the product is safer in various broadcast, printed, or on-line advertising, mentioning that the product is safer in a description of the product on the Internet, mentioning that other similar products are not as safe or are more likely to cause a fire or harm to external materials, or the like.
Various embodiments of the invention, and particularly methods in accordance with the invention, may include the step of distributing the product (step 108). Electronic devices such as surge suppressors, for example, may be distributed (step 108) through distributors, retailers, stores, or the like, or may be sold over the Internet, by mail order, or by telephone as other examples, or a combination thereof. Products may be distributed to end users or consumers, for instance, who may use the products in home or office environments, for example. In certain embodiments, advertising that a product such as an electronic device or surge suppressor is safer (step 107) may help potential customers to select the safer product, thus resulting in greater overall distribution of such a product (step 108), and greater overall benefit to society.
It should be noted that the detailed description of examples of embodiments herein makes reference to the accompanying drawings, which show examples of embodiments by way of illustration and its best mode. While these examples of embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical changes may be made without departing from the spirit and scope of the invention. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, unless stated otherwise, the steps recited in the method or process descriptions may be executed in any order and are not limited to the order presented.
In addition, the terms “first,” “second,” “third,” “fourth,” and the like, herein, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Furthermore, the terms “left,” “right,” “front,” “back,” “top,” “bottom,”“over,” “under,” “up”, “down”, “above”, “below” and the like in this document, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.
Further, benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and element(s) that may cause benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or required elements of the invention. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.”
