Patent Grant
9786454
This disclosure relates to a commutating switch, for example a circuit breaker.
In order to open any DC circuit, the inductive energy stored in the magnetic fields due to the flowing current must be absorbed; it can either be stored in capacitors or dissipated in resistors (arcs that form during opening the circuit are in this sense a special case of a resistor). A great difficulty of using ohmic resistors to define the resistance levels for a commutating circuit breaker is that (1) the transient voltage increase for each resistance level depends on current flowing and resistance inserted at the time of the commutation, and (2) the rate of current increase (during the fault) or decay (after resistance insertion) depends mainly on the inductance in a “dead short” which is the most severe kind of fault, in which the system resistance goes to nearly zero; inductance and system resistance (outside the circuit breaker) can vary a lot in real faults. Therefore, it would be ideal to calculate and define the proper resistance levels to insert each time the circuit breaker operates to reach a target maximum transient voltage difference across the inserted resistor, but this is not practical using ohmic resistors.
When varistors, reversed Zener diodes, or transorbs are put into the circuit, they create an opposed electromotive force (EMF) that absorbs stored energy in a fault; this can be viewed as a highly non-linear resistance, but it is also reasonable to view it more like a battery that loses all the energy put into it during charging, but still manages to control the voltage of the “charging current” fairly well.
Because of the rapid inrush of current in a short circuit, the inductive energy can easily be much greater than just the inductive energy stored in the system at normal full load; if the current goes to five times the normal full load amps before being controlled, the inductive energy would be up to twenty-five times as large as in the circuit at normal full load (depending on the location of the short). Until recently, testing standards for DC breakers have assumed slow operation corresponding to arc chute circuit breakers (the standard DC breaker design since the time of Edison), where the time to open the electrodes is typically greater than or equal to three milliseconds (ms) after the trip signal is received; it can take even longer (up to ten ms) to reach the point at which current begins to decrease. This means that high currents can build up in a short circuit through an arc chute breaker, potentially reaching the maximum capability of the DC power source. For this reason, the DC breaker standard applied in the US to circuit breakers for electric trains (ANSI/IEEE 37.20) requires the circuit breaker to be able to handle 200,000 amperes (200 kiloamps, “kA”), about the maximum short circuit current on a DC fault in an electric train subway system.
A second kind of mechanically switched DC circuit breaker includes the innovative, fast acting high speed vacuum circuit breaker (HSVCB) DC circuit breakers from Hitachi (see for example U.S. Pat. No. 4,216,513) which are based on using inductors and capacitors to create an L-C resonant circuit, coupled with an AC vacuum circuit breaker to break the current as it passes through zero. These circuit breakers expose insulation and circuit components of the normally DC circuit to rapid voltage reversal and voltage spikes. A lower maximum current (50 kA) is allowed by the Japanese regulators (standard JEC-7152) for the L-C resonant circuit breakers for use on DC rail applications compared to the 200 kA that must be withstood by the slower arc chute electric rail breakers. This is enabled by the faster circuit opening action of the L-C based resonant breaker. Essentially in such a breaker, a capacitor discharge (which is triggered electronically) sets up an L-C resonant oscillation which causes the current to oscillate through zero, much like an AC circuit. This oscillation decays rapidly, but during the decay, a vacuum circuit breaker opens the circuit as the current crosses zero. A recent U.S. patent applicationb Ser. No. (13/697,204) shows that this mechanism can also be applied to high voltage DC (HVDC) circuits.
The fastest known way to switch off DC power is to use switchable power electronic devices to open the circuit; these are typically semiconductors, either thyristors or transistors, but vacuum tubes can also be used. In these designs, the resistance of the switch per se is an important consideration, as the full circuit load goes through the switch in the on-state. In the case of the most common type of power electronic switches, the integrated gate bipolar transistors (IGBTs), the typical on-state loss would be between 0.25-0.50% of transmitted power, which is unacceptably large for many applications, and also implies a significant cooling load for high power circuits, which typically requires a pumped liquid coolant. The need for active cooling increases cost and environmental impact, and decreases the reliability of the switch.
ABB has been the main developer of another method to speed up operation of DC switches, including circuit breakers, while maintaining lower on-state losses than purely power electronic circuit breakers, which is a hybrid of power electronic and mechanical switches. In this hybrid method, there are at least two power electronic switches combined with a fast mechanical switch. The first power electronic switch is a low-loss, low voltage-withstand switch that commutates the current to a second path through a second power electronic switch with high voltage withstand capability (but higher on-state losses). Said second power electronic switch may be comprised of a stack of IGBT transistors, a stack of gate turn off (GTO) thyristors, or various kinds of tubes which are capable of shutting off the current. Before said second power electronic switch can be turned off electronically, the low voltage withstand first electronic switch must be protected from the resultant voltage surge by a series-connected mechanical switch; the second high voltage capability shutoff switch cannot open the circuit until the moveable electrodes of the mechanical switch reaches the minimum separation to prevent striking or restriking an arc. This series-connected mechanical switch is the slowest component of the switch, so making it faster makes the hybrid switch faster. The currently used fast mechanical switches have electrodes that are magnetically accelerated via electromagnet repulsion or by a capacitor discharge through a Thompson coil (induced magnetic repulsion), and the electrodes separate in a vacuum or in a gas, which could be a sulfur hexafluoride gas or gaseous mixture.
In hybrid breakers for medium voltage DC (MVDC) said first low voltage withstand switch is desirably an IGCT (integrated gate commutated thyristor); for high voltage DC (HVDC) hybrid breakers, said first low voltage withstand switch is desirably a single stage IGBT that commutates the current over to an IGBT array, with many series-connected IGBTs, with each IGBT in parallel with a metal oxide varistor (MOV). The second high voltage capability shutoff switch can comprise a series connected IGBT transistor array, a stack of gate turn off thyristors (GTOs), a cold cathode vacuum tube, or a similar power electronic switch capable of shutting off the power flow.
There is reported to be about a 100 microsecond response delay time in a Thompson coil actuated mechanical switch due to mechanical response of the connected electrode.
If the hybrid switch is also a circuit breaker, there must also be an energy absorbing snubber such as a semiconductor blocking device or a capacitor bank (for example) to absorb the inductive energy stored in the magnetic fields created by the current. The hybrid breaker described above is an example in which most of the stored inductive energy in an HVDC circuit, which can be more than 100 megajoules, is absorbed by a semiconductor blocking device during operation of a circuit breaker.
This disclosure comprises a mechanical switch that works by commutation of the current to an energy absorbing path or sequence of paths through at least one blocking semiconductor to open the circuit, wherein said commutation is caused by a sliding motion of at least one shuttle electrode over at least one stationary electrode. Said blocking semiconductor can comprise a varistor (such as a polymer-matrix varistor or a metal oxide varistor, “MOV”), a Zener diode (effective for blocking in one direction only, the reverse direction), or a transient voltage suppression diode (bi-directional blocking up to a breakdown voltage). Said blocking semiconductor absorbs at least part of the stored inductive energy to enable circuit opening with controlled maximum voltage (transient voltage suppression diodes are referenced as a “transorb” herein). In order for the sliding switch to not arc upon electrode separation, at least one of these electrodes preferably has a region of increasing resistivity that forms the last part of said electrode to connect electrically to the matching electrode defining the on-state circuit through the switch. In the normal on-state the current passes through the low resistance portion of the matching electrodes, but as the switch opens, current is commutated to at least one well-defined second energy absorbing path through a non-linear, non-ohmic resistor that blocks the current below a threshold breakdown voltage such as a varistor (which could be a polymer-matrix varistor or a metal oxide varistor, “MOV”) or a transient voltage suppression diode or a Zener diode; all such voltage-limiting semiconductor devices are referenced as a “blocking semiconductor” herein.
Said variable resistivity trailing edge portion of the electrode can be attached to a shuttle electrode, a stator electrode, or preferably to both. The graded resistivity in the electrode trailing edges prevents formation of an arc upon electrode separation, for an experimentally defined range of fault conditions as to voltage, current, capacitance, and inductance; current and inductance are particularly important, as they determine the amount of stored magnetic energy in the flowing current which must be dissipated or stored to open the circuit.
The switch commutates the current to at least one parallel path through a blocking semiconductor. Using two or more blocking semiconductors can divide the voltage, provide a useful safety margin, or lower the voltage excursion during switching. It is also desirable in some cases that said blocking semiconductor device be integrally connected to a stator electrode over which a shuttle electrode moves, so as to produce a voltage gradient in the stator electrode. The switches of this disclosure are equally applicable to AC or DC power, but have particular advantages for the DC power case.
This disclosure features a commutating switch. The switch may have a stationary portion with a stationary electrode, and a movable portion with a movable electrode. A switch closed position may be defined when the stationary and movable electrodes are in conductive contact, and the movable portion can be moved relative to the stationary portion to break the conductive contact between the stationary and movable electrodes so as to define a switch open position. There may also be a non-linear, non-ohmic blocking semiconductor in an electrical path into which current is commutated as the switch is opened.
The movable portion may comprise a shuttle, or may comprise a rotor. The stationary and movable electrodes may be contained in a dielectric liquid that is at a hydraulic pressure of at least one MPa, and more specifically may be greater than ten MPa. The stationary portion may comprise two stationary, spaced electrodes, and separate electrical paths may be linked through the two stationary, spaced electrodes.
The stationary electrode may comprise a plurality of adjacent separate conductors. As the switch is opened the movable electrode can make electrical contact with one of the separate conductors at a time. Or, as the switch is opened the movable electrode can make electrical contact with at least two of the separate conductors at the same time.
The commutating switch may have a number of non-linear, non-ohmic blocking semiconductors in the electrical path into which current is commutated as the switch is opened. The plurality of non-linear, non-ohmic blocking semiconductors may be arranged in a stack. The non-linear, non-ohmic blocking semiconductors may be metal oxide varistors (MOVs) arranged in a stack in such a way that motion of a commutating electrode moves current through increasing numbers of MOVs, resulting in stepwise increases of voltage across the stack. The MOVs can be arranged so that edges of a foil holding the MOV extend all the way to a zone where direct contact with a moving shuttle electrode occurs, so that the voltage change between neighboring foils is no more than four volts under normal operating conditions.
The stationary portion may be a stator and the movable portion may be a rotor. The rotor may be held stationary in part by friction arising from a tight-fitting stator that is in contact with the rotor over a substantial portion of the surface area of the rotor. The stator may surround the rotor, and the stator may comprise interchangeable keystone-shaped members. The keystone-shaped members may be held against the rotor by an elastic force or an external hydraulic pressure operating on an impermeable membrane that surrounds the keystone-shaped members. The stator may comprise multiple commutation stages, each stage comprising two commutation zones each comprising a conductive lead, multiple stator electrodes that are each electrically coupled to the conductive lead, and a resistor between each stator electrode and the conductive lead, wherein the two conductive leads of the two zones of each stage are electrically connected through a blocking semiconductor. At least some of the stator electrodes may comprise liquid metal.
The electrodes may slide apart. One or both of the stationary and movable electrodes can have a region of graded, increasing resistivity that forms the last part of the electrode that connects electrically with the other electrode when the switch is moved from the closed to the open position.
The commutating switch can include at least two blocking semiconductors in series electrical paths. The stationary portion may comprise a series of stacked metal oxide varistors. The varistors may be annular and of different outside diameters. The movable portion of the switch may be under stress in the closed position. The blocking semiconductor may be selected from the group of semiconductors consisting of a varistor, a Zener diode and a transient voltage suppression diode.
This disclosure relates to solid state mechanical switches that are able to open a circuit without generating arcs between the separating electrodes. This disclosure builds on the disclosure of PCT/US2012/058240, the disclosure of which is incorporated in its entirety herein by reference.
The present disclosure comprises blocking semiconductors in place of some or all of the ohmic resistors of the subject PCT application. Such blocking semiconductors include but are not limited to varistors, Zener diodes and transorbs; in all of these current is clamped below a breakdown voltage, defined in terms of a critical current density (0.001 amp per square centimeter, for example). All the blocking semiconductors can be compared in terms of breakdown voltage (voltage where current begins to flow), effective voltage control range (voltage range where the blocking semiconductor usefully controls voltage across its terminals), energy-absorbing capabilities, and life expectancy. A difference between metal oxide-based varistors (MOVs) and transistors such as Zener diodes and transorbs is in the fatigue life. MOVs are degraded every time they are used. They are degraded far more by a large energy pulse than a small one, and keeping track of the state of the MOV can become a maintenance problem. With careful monitoring, MOVs can reliably be re-used, but for designing a low maintenance switch or circuit breaker, transorbs are much preferred technically, though they are more expensive.
Because of the arc-less mechanism of quenching the electrical energy, the switches of this disclosure are particularly advantageous for DC electricity, though they may be used for AC electricity as well. This disclosure also relates to more compact switches because the total electrode displacement to achieve a given level of voltage withstand can be reduced compared to air, vacuum, or gas designs. In the particular case of rotary-motion switches, a high pressure dielectric liquid environment (which inhibits arc formation) can be maintained around the switching mechanism using only a small volume of liquid.
This innovation uses highly non-linear resistors (blocking semiconductors) in the switch such that it is not necessary to commutate over many resistive steps to open the circuit. Prior switches have used varistors, transorbs, or Zener diodes to perform the final circuit opening, but only after absorption of most of the stored inductive energy by an array of ohmic resistors. The present innovation recognizes that it is desirable to absorb a large portion of the stored inductive energy with highly non-linear resistance semiconductor devices such as varistors or transorbs. Prior commutating switches relied on multiple commutations of the current through multiple paths to quench the inductive energy. In the presently disclosed switch a single commutation to a blocking semiconductor can open the circuit. One fundamental advantage of using a blocking semiconductor to do the final circuit opening is that the voltage is nearly constant during the period of absorbing the inductive energy, whereas in order to absorb most of the inductive energy with ohmic resistors requires multiple commutations of resistors into the circuit, after each of which voltage increases, followed by an exponential voltage decay. Aside from the complexity of the mechanism to accomplish the multiple commutations of resistors into the circuit, the repeated exponential decays must have an average voltage below the maximum voltage, which is the key factor for insulation of the switch. Maximum voltage must be limited to control damage done to dielectric components by high voltage transients. Since the inductive energy is quenched as the integral of (voltage) X (current) evaluated over time, maintaining a consistent high voltage near the maximum voltage during quenching (as can be accomplished with blocking semiconductors) can result in faster quenching for the switches of this disclosure compared to other switches. Alternatively, the maximum voltage can be reduced without extending the time to quench the inductive energy.
Electrons move through the switch of
There are two pairs of side-by-side stator electrode segments 109 and 144, and a second pair of stator electrode segments 129 and 144 which are linked through the blocking semiconductors 110 or 130. These side-by-side stator electrode segments are electrically connected via the linking wires 108 and 128 to each other and to the blocking semiconductor 110 or 130. The entire rotary switch is enclosed in a pressure vessel 141 that is filled with high pressure dielectric insulating oil 143. In actuality, the volume of high pressure dielectric oil will generally be much less than is shown in the drawing because the inner edge of the high pressure vessel 141 would desirably nearly mate with the outer edges of the keystones (105, 107, 109, 125, 127, 129, 140, 142 and 144) that form the solid stator which contacts the rotor, so as to minimize the volume of high pressure dielectric fluid. A means (not shown) to hold the keystones against the rotor is also needed, such as a stretched elastomer sleeve or a fluid filled sac (containing fluid at higher pressure than the fluid surrounding the electrodes) that is interposed between the pressure vessel 141 and the outside of the 24 keystone segments making up the stator. In the case that keystone segments are held against the rotor by a fluid filled sac or sacs, the pressure within the sacs can be adjusted to adjust the normal force of the keystone segments against the rotor.
At the end of the rotation of the rotor by angle 120, both blocking semiconductor devices are in the circuit. In the case of a high inductance fault, most of the inductive energy that is quenched during opening of the circuit is absorbed by the blocking semiconductors, and a smaller amount by the semiconductive stator electrodes 107, 127. In a low inductance, low current fault, the inductive energy may be mostly or even completely absorbed by the semiconductive stator electrodes 107, 127. It would also be possible for the
The first commutating zone and the second commutating zone together with insulated conductor 220 form the first of three commutation stages in the commutating circuit breaker of
The multistage rotary commutating circuit breaker of
In the device of
The perspective in
In the particular design of
The six commutation zones of
The trailing edges of the conductive electrodes of
To achieve a target of losing 1.0 kW to on-state losses at 2000 amps in the closed circuit condition, the total resistance of the path from Pole A to Pole F in
The spring or other driver used to cause the counterclockwise radial acceleration of
Eighteen ohmic resistance insertions occur during the opening of the circuit of
A useful modification of the design of
When the circuit is closed there is a low resistance path from Pole A to Pole B through the commutating circuit breaker in this way: Pole A connects through conductor 374 to stator electrode 366 to shuttle electrode 411, which then connects through insulated conductor 410 to shuttle electrode 412, which then connects to stator electrode 381 and from there through conductor 382. There is also a parallel connection from Pole A to 382 through blocking semiconductor 420; this connection through 420 limits the maximum voltage across stage 357. Conductor 382 delivers the electric current to stator electrode 389, then to shuttle electrode 216, then through insulated conductor 415 to shuttle electrode 417, then to stator electrode 396, then through conductor 397 to Pole B. There is also a parallel connection from 382 to Pole B through blocking semiconductor 421; this connection through 421 limits the maximum voltage across stage 419.
The multiple stage, linear motion switch in this case is essentially a rigid body that maintains a set geometric relationship between the four shuttle electrodes 411, 412, 416, and 417 as it moves to the right to open the circuit. After the twelve resistive insertions implied by
A long multistage chain of commutating circuit breakers as in
It is easier to submerge the cylindrical commutating rotors of
MOVs can be conveniently produced as stacks of varistor film on layers of metal foil. The next example shows how stacks of such varistor films can be incorporated into the stator of a commutating switch of this disclosure.
Each pair of next neighbor disc MOV layer assemblies (such as 461) is bonded together by some suitable means such as conductive adhesive, soldering, or brazing. The metal washers 451, 452 are very simple examples of stator electrodes, and preferably have a slightly smaller hole 456 through them than the hole 455 through the MOV layers themselves (such as 450), so that the metal washers protrude a little further into the central cavity than the inner radius the MOV elements; in this case it is preferred that a polymer with good electrical withstand, resistivity around 10 to 10^5 ohm-meters, low friction, and good tracking resistance is placed between the inner edges of the metal discs such as 451, 452. This protects the inner surfaces of the actual MOV (such as 450) from damage via direct contact with the moving shuttle electrode 465, which in this case is simply a metal rod or tube that extends clear through the stack of MOV layer assemblies 460. At the bottom end of the shuttle electrode 465 is an optional end 466 of the commutating shuttle 465 which works as an electrical stress control device with a similar function to the trailing edge resistors 155, 164, 157, and 168 of
In the on-state, electrical connection to Pole A is made by low resistance stator electrode 490 which can be a high conductivity metal electrode or a liquid metal electrode that mates with the end of shuttle electrode 465. There is a parallel path from Pole A to the bottom of the stack of MOV layer assemblies via electrical contact 485, and then from the upper edge of the MOV stack through connector 486 and conductor 487 to pole B. As the shuttle electrode 465 is withdrawn during operation of the switch, the connection through an increasing length of the MOV stack 460 becomes the only electrical connection between the poles. This parallel path through the MOV stack 460 remains connected before and after operation of the switch as
It is desirable that the lowest disc-shaped MOV layer assembly in
The circuit breaker of
Amax=σ/LD (3)
Results from this equation appear in Table 1 for a 2 meter long column of metal pulled from one end as in
The best overall solution for a commutating shuttle 465 as in
The fastest actuation commutating circuit breaker of
M={(strength)/[density×resistivity]}/{(strength)/[density×resistivity] for annealed copper}
This figure of merit M is indexed to a reference value for annealed copper of 1.00; higher values of M are more desirable. Of the single component or alloy materials (not composites or fabricated structures) shown in Table 1, cold worked copper has a modestly improved figure of merit M (1.257) compared to copper, and all the forms of magnesium and aluminum examined also have slightly higher M value than annealed copper, ranging from 1.147 to 4.411 for high strength aluminum alloy 6061-T6. The highest figure of merit M in Table 1 (6.424) is for a cermet wire, composed of alumina glass fibers in a matrix of pure aluminum. Such a cermet wire can serve as both conductor and actuator of the motion of the commutating shuttle 465 in
Because the modulus of the cermet wire (core wire of 3M ACCR) is so high (4550 MPa), stretching it just a few percent can store a large amount of elastic energy (comparable to a very stiff spring) that could supply force 480 while obviating the need for slip ring 470. This design could be used for a very fast actuating design capable to very high voltage. In the most extreme version, it is possible to stress a cermet ACCR wire up to close to its breaking strength (1400 MPa), with the wire strung through an MOV stack such as that shown in
This type of circuit breaker would be resettable without replacing components only for option 1. The last two methods would still be useful as a form of fast fuse for HVDC circuits that only blow rarely; they too can be reset, however one part (the fuse) needs to be replaced each time. A commutating circuit breaker of
The design of
All mechanical electrical switches face similar limitations on maximal speed of action. There is always a moveable electrode and the maximum speed of opening the circuit depends on how long it takes for the electrodes to move far enough apart to either quench the arc or other current between the electrodes and prevent restriking an arc. The disclosed switch speeds action of a mechanical switch because the separating electrodes are insulated by high dielectric strength solids and liquids, which can be at high contact or hydraulic pressure to maximize electrical withstand during opening of the electrodes. The absence of gas in the region between the separating electrodes in some versions of the inventive design reduces the electrode separation that is required to prevent restriking an arc; this is true even in the case of a mechanical switch that is opened with no power flowing, but re-energized shortly thereafter, as is normal in various hybrid circuit breaker designs. This allows faster completion of action by the mechanical switch portion of various hybrid switch designs, since the fast mechanical switch of this disclosure does not have to move as far as prior art switches to prevent restriking an arc.
The concepts disclosed herein can be implemented in either rotating or linear motion designs, and preferably utilizes graded resistivity on the trailing edges of electrodes to commutate the power with little or no arcing. Positioning and restraint of stressed shuttle electrodes in the on-state via piezoelectric brakes and correlated magnetic domains, where the shuttle is under stress in the on-state was mentioned in PCT/US2012/058240 and can also be applied to the switches of this disclosure. A further improvement that is added in this disclosure is to use the normal force-mediated frictional force to restrain the motion of the commutating shuttle in the on-state.
The suppression of arcing in the commutating switches of this disclosure relies on three features:
One aspect described in PCT/US2012/058240 is to provide a switch primarily insulated by solid dielectrics that fit tightly around the electrodes so as to minimize the size of any fluid-filled cracks that may form between the electrodes during separation; this increases the ability to withstand a given voltage between the electrodes. Note though, that this implies a normal force between the shuttle and stator which is also useful for restraining the force applied to the stator to cause its motion. Such switches by their nature imply significant frictional interaction between the moveable shuttle or rotor electrodes and dielectric solids which are bonded to the moveable electrodes with the surrounding stators, including both stator electrodes and portions of the insulating solid dielectric parts of the stator, which partially constrains motion of the moveable electrodes both before and during switching. Said frictional interaction can be advantageously used in rapid methods of triggering of electrical switches, because the stick-slip nature of the frictional interaction can be used to partially restrain motion of the shuttle electrode prior to triggering. To be specific, static friction is normally greater than kinetic or sliding friction, so a frictionally locked stator in which the critical force to begin motion F(CR) is greater than the actual applied force F(AP) can stably hold its position for a long time, and yet be capable of sustained motion at the same applied force once the motion begins. This makes it possible to trigger motion of the shuttle electrode by providing an extra “kick” of triggering force F(TR) that gets the shuttle moving. After the shuttle is in motion, it will continue to move until the motive applied force F(AP) drops below the critical dynamic force F(DYN). Insofar as the critical force to begin motion F(CR) is proportional to the normal (perpendicular) force between the shuttle and the stator, it is practical to adjust F(CR) by adjusting the pressure around a flexible stator which in turn adjusts the normal force between the shuttle and stator.
Hydraulic cylinders or fluid-filled fiber-reinforced elastomeric bags (similar to high pressure hydraulic hoses) may desirably be used to apply a normal force to the interface between a shuttle and a stator in the switches of this disclosure. This can be visualized by reference to
The modular stator assembly can also be held tightly against the commutating rotor by a stretched elastomeric sleeve that surrounds the outer perimeter of the modular stator assembly.
Although features of the claimed invention are shown in some drawings but not others, this is not a limitation of the scope of the invention. Other examples will occur to those skilled in the field and are within the scope of the claims.
This application is a continuation of and claims priority of PCT Application Number PCT/US14/49714, filed on Aug. 5, 2014, the disclosure of which is incorporated herein by reference. The subject PCT application claimed priority to Provisional Patent Application 61/862,111, filed on Aug. 5, 2013.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4216513 | Tokuyama et al. | Aug 1980 | A |
| 5193041 | Chanois | Mar 1993 | A |
| 5218508 | Doone | Jun 1993 | A |
| 5339210 | Howell | Aug 1994 | A |
| 5909350 | Anthony | Jun 1999 | A |
| 6128168 | Arnold | Oct 2000 | A |
| 6751078 | Munakata et al. | Jun 2004 | B1 |
| 7662208 | Kikuchi et al. | Feb 2010 | B2 |
| 8995097 | Skarby | Mar 2015 | B2 |
| 9484168 | Pessina | Nov 2016 | B2 |
| 20020070694 | Blum | Jun 2002 | A1 |
| 20070197051 | Cravey et al. | Aug 2007 | A1 |
| 20120199558 | Faulkner | Aug 2012 | A1 |
| 20140110376 | Zahlmann | Apr 2014 | A1 |
| 20170018390 | Jaenicke | Jan 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 2320535 | May 2011 | EP |
| 2011161121 | Dec 2011 | WO |
| 2012146517 | Nov 2012 | WO |
| 2013049790 | Apr 2013 | WO |
| 2015021010 | Feb 2015 | WO |
| Entry |
|---|
| The International Preliminary Report on Patentability issued on Feb. 18, 2016 for corresponding application No. PCT/US2014/049714. |
| The International Search Report and the Written Opinion of the International Searching Authority issued on Dec. 10, 2014 in Corresponding Application No. PCT/2014/049714. |
| Number | Date | Country | |
|---|---|---|---|
| 20160254109 A1 | Sep 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61862111 | Aug 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2014/049714 | Aug 2014 | US |
| Child | 15016437 | US |
