Line dispensing devices, such as auto-belay devices used for climbing or descender devices for workers or conveyances, can be used to protect against falls by retracting slack when the line is not under load and providing a braking force when the line is loaded, so that the weight (e.g., climber) on the end of the line descends at a safe speed. Line dispensing devices can include various braking systems that generate the braking forces. These braking systems can include friction-based systems, hydraulic-based systems, electromagnetic-based systems, and magnetic-based systems (e.g., an eddy current braking mechanism).
This disclosure describes examples of a line dispensing device, such as an auto belay device used for climbing activities or descender devices for workers or conveyances. In the line dispensing device described herein, features are described that increase the performance of the device. For example, increased reactivity of the braking and retraction assemblies so that the device is more responsive to climbers needs. In another example, the life-cycle of the device is increased by increasing its loading capacity. Additionally, features are described that increase manufacturing and assembly efficiencies. For example, the entire device is enabled to be more quickly and accurately assembled and disassembled (e.g., during service and inspection processes). Accordingly, a higher performing and more efficient line dispensing device is provided.
In an aspect, the technology relates to a line dispensing device including: a housing; a rotatable shaft rotatably supported by the housing and defining a rotational axis; a line drum disposed about the rotational axis and configured to extend and retract a line from the housing; a retraction assembly disposed about the rotational axis and configured to generate a retraction force and retract the line from the housing; and a braking assembly disposed about the rotational axis and configured to generate a braking force on the line and during extension of the line from the housing.
In an example, the braking assembly includes a rotor assembly having one or more conductors and a stator assembly having one or more magnets, and the rotor assembly is coupled to the rotatable shaft and rotatable around the rotational axis so as to generate an eddy current braking force. In another example, the stator assembly includes a pair of plates each having a plurality of keys extending therefrom, and the one or more magnets are coupled to the pair of plates and the plurality of keys at least partially define a polarity orientation of the one or more magnets. In yet another example, the line drum is coupled to the rotatable shaft and rotatable around the rotational axis, and the line drum is rotatable around the rotational axis at a different speed than the rotatable shaft. In still another example, a transmission is coupled between the line drum and the rotatable shaft so that rotation of the line drum drives rotation of the rotatable shaft. In an example, the retraction assembly is coupled to the line drum and rotatable around the rotational axis, and the retraction assembly is rotatable around the rotational axis at a different speed than the rotatable shaft.
In another example, one end of the rotatable shaft includes a female spline connector configured to receive another exterior shaft and drive rotation thereof. In yet another example, the braking assembly is an eddy current braking device, a hydraulic braking device, a friction braking device, or an electromagnetic braking device.
In another aspect, the technology relates to a line dispensing device including: a line drum housing a line and configured to rotate about a rotational axis during extension and retraction of the line; a rotatable shaft rotatable around the rotational axis; and a transmission extending between the line drum and the rotatable shaft so that rotation of the line drum drives corresponding rotation of the rotatable shaft.
In an example, the transmission includes: a sun gear coupled to the rotatable shaft; an internal gear co-axial with the sun gear and fixed relative to the rotational axis; and a plurality of planet gears meshed with the sun gear and the internal gear, the plurality of planet gears are supported on the line drum. In another example, the line drum includes: a pair of drum plates; and a hub supported on the rotatable shaft, the line is wrapped around the hub and disposed between the pair of drum plates, and the hub includes a pair of substantially parallel planer surfaces. In yet another example, the hub further includes at least one arcuate projection configured to receive at least a portion of a short webbing for coupling the line to the line drum. In still another example, a housing has a nozzle that the line extends through, the nozzle includes a pair of covers that are pivotably coupled to the housing. In an example, a guide roller is proximate the nozzle, the guide roller is rotatably supported by a pair of shoulders defined by the housing.
In another example, a retraction assembly is coupled to the line drum, the retraction assembly includes: a hub supported on the rotatable shaft; a coil spring coupled to the hub; and a pair of flexible plates sandwiching the coil spring therebetween.
In another aspect, the technology relates to a line dispensing device including: a housing defining an interior cavity and an external cavity; a rotatable shaft rotatably supported by the housing and defining a rotational axis, wherein one end of the rotatable shaft is cantilevered within the external cavity; and a braking assembly at least partially disposed within the external cavity and configured to apply a braking force on the rotatable shaft, wherein the braking assembly includes: a stator assembly coupled to the housing; and a rotor assembly coupled to the rotatable shaft and rotatable around the rotational axis.
In an example, the stator assembly includes a pair of plates that have an outer perimeter with one or more male pins that selectively engage with corresponding female receptors defined within the external cavity. In another example, the rotor assembly includes: a pair of rotor plates having at least one bent tab extending therefrom; one or more conductors pivotably coupled to the pair of rotor plates; and at least one biasing element extending between the at least one bent tab and the one or more conductors. In yet another example, the biasing element includes hooks or loops at each end that directly engage with the at least one bent tab and the one or more conductors. In still another example, the line dispensing device further includes: a line drum supported on the rotatable shaft and configured to rotate around the rotational axis; and a retraction assembly supported on the rotatable shaft and configured to rotate around the rotational axis. In an example, the housing defines at least one mounting aperture, and a bushing is coupled to the at least one mounting aperture.
These and various other features as well as advantages that characterize the line dispensing devices described herein will be apparent from a reading of the following detailed description and a review of the associated drawings. Additional features are set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the technology. The benefits and features of the technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing introduction and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The following drawing figures, which form a part of this application, are illustrative of described technology and are not meant to limit the scope of the invention as claimed in any manner, which scope shall be based on the claims appended hereto.
This disclosure describes examples of a line dispensing device, such as an auto belay device used for climbing activities. Although, the features of the line dispensing device described herein can also be used in any other line braking system (e.g., industrial or occupational descender devices, such as personnel, equipment, or training, recreational descender devices, such as conveyances, rides, trolleys, ziplining, free-fall devices, and the like) as required or desired. The line dispensing device provides various improvements for an eddy current braking assembly so as to generate a braking force on the line and control descent of a load attached to the line. However, it should be appreciated that improvements to other operational systems (e.g., line drums, retraction assemblies, etc.) can be used in any other type of line dispensing device (e.g., frictional braking, hydraulic braking, electromagnetic braking, etc.).
In the line dispensing device described herein, features are described that increase the performance of the device. For example, increased reactivity of the braking and retraction assemblies so that the device is more responsive to climbers needs. In another example, the life-cycle of the device is increased by increasing its loading capacity. Additionally, features are described that increase manufacturing and assembly efficiencies. For example, the entire device is enabled to be more quickly and accurately assembled and disassembled (e.g., during service and inspection processes). Accordingly, a higher performing and more efficient line dispensing device is provided.
The line dispensing device includes a housing with an interior cavity and an exterior cavity and a rotatable shaft rotatably mounted thereto. A braking assembly is at least partially coupled to the rotatable shaft and disposed in the exterior cavity. A line drum that houses a main line for the device and a retraction assembly are supported on the rotatable shaft and disposed in the interior cavity. By separating the braking assembly from the rest of the device components, heat generated during use is more efficiently dissipated, thereby increasing performance. Additionally, the braking assembly uses a rotor assembly and a stator assembly so as to decrease the number of rotating components in the device. This results in a system that has a decreased mass and a more efficient rotational moment of inertia when extending and retracting the loaded line.
Additional features of the line dispensing device include components that are sized and shaped to be coupled together in only one orientation and direction. This reduces the overall number of components and increases assembly and disassembly efficiencies. A redundant transmission system is utilized to couple the line drum to the rotatable shaft to drive rotation thereof. By creating a redundant system, the torque loads induced across each component are reduced, thereby increasing the life-cycle capabilities of the device. Further improvements include a nozzle that does not completely release from the housing so that line maintenance and replacement is easier and component parts are not lost or dropped. Many other features of the line dispensing device are described further below.
As used herein, the terms “axial” and “longitudinal” refer to directions and orientations, which extend substantially parallel to a centerline of the component or system. Moreover, the terms “radial” and “radially” refer to directions and orientations, which extend substantially perpendicular to the centerline of the component or system. In addition, as used herein, the term “circumferential” and “circumferentially” refer to directions and orientations, which extend arcuately about the centerline of the component or system.
In some examples, a bushing 114 may line the apertures 108, 110. The bushing 114 decreases wear on the housing 104 from the coupling device(s) (e.g., a carabiner) and are replaceable as required or desired. Additionally, the bushing 114 can decrease friction between the housing 104 and the coupling device(s) so that the line dispensing device 100 can more easily move around during use. Furthermore, the bushing 114 can reduce dynamic vibrations (e.g., provide a damper) between the line dispensing device 100 and the support structure. These vibrations may generate a resonance condition that is undesirable. One example of the bushing 114 is described further below in reference to
In the example, the housing 104 forms an interior cavity 130 via the housing sections 118, 120. The line drum 126 and the retraction assembly 128 are disposed within the interior cavity 130. Additionally, both the line drum 126 and the retraction assembly 128 are supported on a rotatable shaft 132 that is rotatably supported within the housing 104 by a pair of bearings 134. In the example, both the line drum 126 and the retraction assembly 128 are rotatable within the housing 104. The braking assembly 124 is disposed outside of the interior cavity 130 and within an exterior cavity 136 formed on one of the housing sections 118. It should be appreciated that the cover 116 may at least partially cover the braking assembly 124 so that it is not completely exposed on the line dispensing device 100.
The rotatable shaft 132 enables increased safety of the line dispensing device 100 (e.g., gear redundancy), increased functionality of the line dispensing device 100 (e.g., attachment of one or more accessory mechanisms), and increased ability to more reliably and accurately sense, track, and be responsive to status conditions of components (e.g., velocity, change of directions, amount of line dispensed, etc.) during operation of the line dispensing device 100 and as described further herein. In contrast, most, if not all, currently known line dispensing devices have a fixed shaft with components that rotate relative to the fixed shaft.
The braking assembly 124 includes a rotor assembly 138 and a stator assembly 140. The rotor assembly 138 is coupled to the rotatable shaft 132 and thus is also rotatable within the line dispensing device 100. In contrast, the stator assembly 140 is coupled to the housing section 118 and thus is fixed with respect to rotation. In the example, the braking assembly 124 is an eddy current braking mechanism with the rotor assembly 138 having a plurality of conductors 142 and the stator assembly 140 having a plurality of magnets 144. In operation, upon rotation of the rotor assembly 138 the generated centrifugal forces radially displace the conductors 142 in a direction towards the magnets 144 so that braking forces are generated. The braking assembly 124 is described further below in reference to
In the example, the rotatable shaft 132 is supported on the housing sections 118, 120 by the pair of bearings 134 and one bearing 134 is offset and inwards from one end of the shaft 132. As such, one end of the rotatable shaft 132 cantilevers into the exterior cavity 136 and supports the rotor assembly 138. In an aspect, the cantilevered end of the rotatable shaft 132 is shorter in length than the length of the shaft 132 between the bearings 134. In the example, the line drum 126 and the retraction assembly 128 are each disposed between the bearings 134 on the rotatable shaft 132.
By isolating the braking assembly 124 from the line drum 126 and the retraction assembly 128, thermal control of the braking assembly 124 is increased, thereby increasing performance of the line dispensing device 100. During operation of the braking assembly 124, eddy current braking forces can generate heat. The housing section 118 can act as a thermal barrier to reduce or prevent heat from adversely affecting the line drum 126 and the retraction assembly 128. Furthermore, the exterior cavity 136 can be more effectively passively cooled, (e.g., via vents) with only the braking assembly 124 disposed therein. Additionally, by reducing the span lengths of the rotatable shaft 132 that support the operational systems, bending forces are reduced on the shaft 132, thereby increasing performance and resistance to wear (e.g., from shipping and maintenance).
Furthermore, in this example, the number and size of rotatable components are decreased, thereby also decreasing mass. For example, the magnets 144 are stationary and not rotatable. Additionally, all of the rotatable components rotate around a single rotational axis. Thus, the inertia of the rotatable components is reduced so that the braking assembly 124 and the retraction assembly 128 are faster to respond during operation of the line dispensing device 100 since they are at least partially dependent on rotation. This configuration results in increase responsiveness to user's climbing movements and improved performance.
The line dispensing device 100 also includes a guide roller 146 that is disposed proximate the nozzle 106. When the line 102 wraps and unwraps from the line drum 126, the line rolls over the guide roller 146 so as to position the line relative to the nozzle 106 and exit from the housing 104, as well as inducing a smoother extension and retraction of the line without twisting thereof. In the example, the guide roller 146 is rotatable about a fastener 148 that is also used to couple the two housing sections 118, 120 together. The guide roller 146 is also elongated in the axial direction. In an aspect, the axial length of the guide roller 146 is twice or more the thickness of the line 102. In another aspect, the axial length of the guide roller 146 is greater than the axial distance between two drum plates 150, 152 of the line drum 126 and which the line is disposed between. The guide roller 146 is described further below in reference to
The rotatable shaft 132 is coupled to the line drum 126 by a transmission 164 so that rotation of the line drum 126 can drive rotation of the rotatable shaft 132. In the example, the transmission 164 is a planetary gear system with a sun gear 166 that is coupled to and extends from the rotatable shaft 132. In an aspect, the sun gear 166 is a spur gear. The planetary gear system also includes a plurality of planet gears 168 that are rotatably coupled to one of the drum plates 150 and an internal gear 170 coupled to and fixed to the housing section 118. The planet gears 168 are meshed with both the sun gear 166 and the internal gear 170, and in an aspect, are spur gears. The line drum 126 also includes a hub 172 that at least partially surrounds the rotatable shaft 132 and between the drum plates 150, 152. In the example, the hub 172 is supported on the rotatable shaft 132 by one or more bearings 174, and as such, the line drum 126 can rotate around the rotational axis 154 at a different rotational speed than the rotatable shaft 132.
The retraction assembly 128 is directly coupled to the hub 172 so that it rotates with the line drum 126. In the example, one or more fasteners 176 (e.g., bolts) couple the retraction assembly 128 to the hub 172 of the line drum 126. In
In operation, the line 102 is wrapped at least partially around the hub 172 and a free end extends out of the housing 104 via the nozzle 106. When the line 102 is extended and not loaded (e.g., a climber climbing up a climbing wall), the retraction assembly 128 is configured to rotate the line drum 126 around the rotational axis 154 so as to retract the line 102 back into the housing 104 and wrap around the hub 172. This rotation of the line drum 126, via the retraction assembly 128, induces a corresponding, but not necessarily equal, rotation in the rotatable shaft 132 via the transmission 164. The rotor assembly 138 also rotates via the rotatable shaft 132. In the example, the braking assembly 124 generates an eddy current braking force during retraction of the line 102 via retraction assembly 128 so as to decrease wear on the coil spring of the retraction assembly 128. Additionally, by generating a braking force during retraction of the line 102, the retraction of the line is more controlled, for example, during unanticipated line releases.
When the line 102 is loaded (e.g., a climber falling from the wall), the line drum 126 is configured to rotate in the other direction, which overcomes the retraction force generated by the retraction assembly 128, so that the line 102 extends from the housing 104 and unwraps from the hub 172. This rotation of the line drum 126 induces a corresponding, but not necessarily equal, rotation in the rotatable shaft 132 via the transmission 164 to drive rotation of the rotor assembly 138 and extend the conductors 142 into the magnetic field of the magnets 144. This generates an eddy current braking force on the rotatable shaft 132 to control the extension of the line from the housing 104 and the descent rate of the load attached thereto.
In the example, the female receptors 188 within the side wall 180 can receive both male pins 190, 192 from each plate 156, 158. As such, when the plates 156, 158 are mounted to the housing section 118, the male pins 190, 192 can be positioned circumferentially offset from one another. By utilizing the structure of the housing section 118 as supports and connectors to the stator assembly 140, efficiency and performance of the line dispensing device is increased. For example, assembly efficiencies are increased as the braking assembly 124 can only fit together in one configuration and there are less overall components to assemble. Additionally, performance is increased because the number of rotating components are decreased. Furthermore, although a bayonet type coupling connection is shown and described, it is appreciated that the stator assembly 140 can be mounted within the exterior cavity 136 via any other connection type as required or desired. In other examples, the male pins 190 on the inside magnet plate 156 need not to be used, and the inside magnet plate 156 can be only coupled to the housing section 118 via fasteners 186. In still other examples, the male pins on the inside magnet plate 156 can be replaced by one or more notches (not shown) that are configured to engage with one or more corresponding protrusions (not shown) disposed within the exterior cavity 136 of the housing section 118. In this example, the notches and protrusions are utilized for orienting the inside magnet plate 156 with respect to the housing section 118.
A plurality of conductors 142 are pivotably mounted between the rotor plates 196, 198 at fasteners 206 (e.g., through bolts) that extend through openings 208 in the plates 196, 198. In an aspect, three conductors 142 are included in the rotor assembly 138 and are formed from a non-ferritic material (e.g., a high grade aluminum for greater conductivity and increased braking performance). The conductors 142 include a pin 210 that is configured to be slidable received within tabbed openings 212 defined within each plate 196, 198. A spring tab 214 extends axially from the plates 196, 198 and is disposed proximate the tabbed openings 212. Each conductor 142 includes one or more biasing elements 216 (e.g., tension springs on each plate side) that are connected at one end to the pin 210 and at the other end to the tab 214. In operation, centrifugal forces induced on the conductors 142 from rotation of the rotor assembly 138 cause the conductors 142 to radially extend out from between the plates 196, 198. This movement generates braking forces due to interaction with a corresponding magnetic field, and the system is described further in U.S. Pat. Nos. 8,490,751 and 8,851,235.
In this example, the biasing elements 216 have loops or hooks at each end so they can directly engage with the pin 210 and the tab 214 without the need for connection plate elements. Furthermore, the tab 214 is integral with the plates 196, 198 so as to reduce the number of components and to simplify structural support of the conductors 142. These configurations increase assembly efficiencies of the rotor assembly 138. Additionally, by containing the components of the rotor assembly 138 with the plates 196, 198 the entire assembly is easier to handle and move in and out of the line dispensing device. In the example, the spring tab 214 is adjacent and forms part of the tabbed opening 212. In other examples, the spring tab 214 may be positioned outside from the opening 212, but still adjacent thereto.
The outside plate 158 includes an outer ring section 218 that the magnets 144 are configured to mount to and an inner section 220. The inner section 220 restricts access to the rotor assembly 138 (shown in
The outer ring section 218 also includes a plurality of keys 228 extending therefrom and a plurality of lugs 230 extending therefrom. The keys 228 and the lugs 230 are configured to correctly place and space the magnets 144 attached thereto. The lugs 230 are circumferentially arranged so that a magnet 144 can be placed between a pair of lugs 230. As such, the correct array of magnets 144 are easily achieved when the stator assembly is being assembled. The magnets 144 themselves are magnetically coupled to the outside plate 158 and adhesive or glue is not necessarily required. The lugs 230 also restrict or prevent circumferential movement of the magnets 144 on the outer ring section 218. Additionally, because the plate 158 is stationary in the line dispensing device, the thickness of the plate 158 can be reduced to save weight without attenuating braking power. In the example, the lugs 230 are substantially cylindrical in shape. In other examples, the lugs 230 can be of any other shape as required or desired.
Each magnet 144 includes an aperture 232 that is configured to receive the key 228. The aperture 232 is offset from a centerline of the magnet 144 and the key 228 is disposed between the pair of lugs 230, but also offset from a centerline between the pair of lugs 230. This arrangement of the keys 228 requires a predetermined placement of the magnets 144 so as to ensure the correct north-south polarity at the specific location on the plate 158. That is, the structure of the plate 158 (e.g., via the keys 228, the lugs 230, and the apertures 232) forces the magnets 144 to be installed in the correct polarity, because if the polarity is reversed, the keys 228 do not align with the apertures 232.
The inside plate 156 also includes an outer ring section 234 that the magnets 144 are configured to mount to. In the example, the inner section of the inside plate 156 is free from any structure to reduce weight thereof. The outer perimeter of the outer ring section 234 includes male pins 190 that enable the inside plate 156 to be mounted to the housing section 118. In the example, the male pins 190 include radially long pins 236 and radially short pins 238 that both selectively engage with the female receptors 188 of the housing section 118 so as to ensure proper plate 156 placement. Additionally or alternatively, one or more notches (not shown but similar to the notch 226 shown in the plate 158) may be defined on the outer perimeter of the outer ring section 234 and used to orient the inside plate 156 with respect to the housing. The inside plate 156 also includes one or more holes 240 that receive the fastener 186 (shown in
The inside plate 156 also includes keys 228 and lugs 230 to ensure assembly of the stator assembly in the correct north-south polarity configuration of the magnets 144. The male pins 190, 192 of each plate 156, 158 are configured to selectively engage with the housing section 118 so that the plates 156, 158 and magnets 144 can only be mounted in a single orientation and to prevent incorrect assembly. In an aspect, both plates 156, 158 can be formed from a ferritic material so that the magnets 144 are attracted to the plate and can be attached without glue, and the thickness of both the outside plate 158 and the inside plate 156 can be substantially equal so as to increase manufacturing efficiencies.
The line drum 126 also includes the transmission 164 that translates rotation of the hub 172 and drum plate 150 to rotation of the rotatable shaft 132. The transmission 164 includes the internal gear 170 that is statically mounted to the housing section 118 (shown in
In the example, three planet gears 168 are shown and by using a plurality of planet gears 168 a redundant load bearing system is formed. Additionally, by transferring torque over three gears 168 instead of one gear, the torque is distributed over three components instead of one component so that the life-cycle of the transmission 164 is increased. Furthermore, the transmission 164 can operate with increased torque loads. It should be appreciated that any other number of planet gears, for example, two, four, five, etc., can also provide similar benefits to the transmission 164 described herein.
When the short webbing 246 is wrapped around the hub 172, the thickened reinforced section 250 and the shackle 252 are thicker sections that can form bumps in the line 102 as it wraps around the hub 172. As such, the planer surfaces 254 are used so that when the short webbing 246 is wrapped around the hub 172, the thickened reinforced section 250 and the shackle 252 are disposed proximate the planer surfaces 254 so that the line 102 can more concentrically wrap around the hub 172 without any undesirable bumps. That is, the planer surfaces 254 form space in the hub 172 for the thickened reinforced section 250 and shackle 252 to sit within the line drum. The hub 172 also includes one or more openings 258 that are configured to receive fasteners 176 (shown in
In the example, the coil spring 263 of the retraction assembly 128 is axially positioned between two plates 266. The plates 266 can be formed from a flexible light weight plastic-based material that is not coupled to the coil spring or the hub 260. By sandwiching the coil spring 263 between two plates 266, the coil spring 263 can more easily be assembled onto and removed from the hub 260 without the coil spring 263 axially de-coiling. In an aspect, the plates 266 are identically circular in shape with a center opening 268 that the hub 260 is disposed within. In another aspect, the plates 266 may have different shapes and/or each plate 266 may have a different shape. The plates 266 also enable the coil spring 263 to be more easily inspected without disassembly and removal. For example, the housing section 120 may include one or more slots 270 that allow the coil spring 263 within the plates 266 to be inspected and that assist in removing the coil spring 263 from the housing.
The mount damper 296 has a substantially hollow cylindrical body 298 with a first end 300 and a second end 302. The first end 300 has a first flange 304 extending therefrom and the flange 304 is continuous around the perimeter of the first end 300. The second end 302 has a second flange 306 extending therefrom and the flange 306 is discontinuous around the perimeter of the second end 302. For example, the second flange 306 is separated into four discrete sections. The flanges 304, 306 protect at least a portion of the sides of the housing 104 from the coupling device. Additionally, the body 298 is formed from an elastomeric material so that the second flange 306 can be inserted into the aperture 108 by at least partially compressing its diameter to be smaller than the aperture 108 via the sectional second flange 306.
In operation, the coupling devices (e.g., carabiner) utilized to couple the line dispensing device 100 to a support structure can induce wear on the housing 104 at the mounting aperture 108. The mount damper 296 is a sacrificial component that is easily replaceable to protect the housing 104 and absorb the wear from the coupling device. Additionally, the mount damper 296 provides shock absorption such that vibrations are reduced or prevented from being transmitting between the housing 104 and the coupling device.
It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods and systems within this specification may be implemented in many manners and as such is not to be limited by the foregoing exemplified embodiments and examples. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment and alternate embodiments having fewer than or more than all of the features herein described are possible. It is to be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
While various embodiments have been described for purposes of this disclosure, various changes and modifications may readily suggest themselves to those skilled in the art and may be made which are well within the scope of the present disclosure.
This application claims priority to and the benefit of U.S. Provisional Application No. 62/991,467, filed Mar. 18, 2020, which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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62991467 | Mar 2020 | US |