Patent Application
20230060108
We, Christopher Caddock, an invention of the present invention described herein, having an address at 18 Mayberry Road, Chappaqua, N.Y. 10514, a citizen of the United States of America; and Donald Platt, an inventor of this present invention described herein, with an address at 2211 Santa Lucia Circle, Melbourne, Fla., a citizen of the United States of America have conceived an invention titled “Catalyst System for Rocket Engine.”
The field of the invention relates to the design and development of a rocket engine, and more specifically, the present invention relates to the design of a catalyst system adapted for an Aerospike rocket engine and further relates to improvements to aid in the creation of a more lightweight, reliable, efficient rocket engine.
Conventional rocket engine technologies utilize chemical combustion in single and multistage engines to reach the upper atmosphere. The weight of the fuel and efficiency of the engine at varying altitudes often dictate current designs. In certain multistage rockets designed for orbit, when the first stage of a rocket ignites, the engine, which may be more efficient at lower altitudes, causes the rocket to lift into the atmosphere gradually. Thereafter, the first stage separates from the upper stage and ignites a subsequent engine, which may be more effective at higher altitudes. The upper or second stage may be needed to enable a payload to reach the earth's lower orbit. A more efficient, lighter, and more cost-effective design is needed.
Conventional rocket engine technologies often utilize a convergent-divergent nozzle, such as a bell nozzle, which converts the heat of exhausting flue gas into pressure (or thrust). Preferably in designing such a nozzle, the pressure of the resulting exhaust is provided to be about the same pressure as the atmosphere into which the exhaust exits. In an over-expanded nozzle, the atmospheric pressure is higher than the exhaust; the result is the opposite in an under-expanded nozzle. However, in an over-expanded state and under-expanded state, the engine does not provide optimal efficiency for conversion of fuel to thrust. Accordingly, given typical environmental constraints, designers of bell nozzles attempt to provide the best physical configuration for the bell nozzle to allow an optimal thrust for an expanded fuel mixture over a range of altitudes and atmospheric pressures that are anticipated. The bell nozzle may be under-, over-, or ideally expanded during an ascent of a flight profile; however, the inefficiency is a tradeoff for a single configuration of the nozzle for the desired engine and fuel type. See
An aerospike engine is an alternative design utilizing an aerospike nozzle rather than a bell nozzle. Designs of aerospike nozzles can vary and include annular and linear versions. See
Several aerospike engines were tested from 1997 to 2000. Because of technical problems, inherent constraints of the physical systems and materials, and high costs, the tests were discontinued. Among earlier attempts, the X—33 vehicle, a half-scale demonstrator for the proposed “Venture Star” orbital space plane, utilized a prototype aerospike engine and attempted to address certain expected issues with new technologies to be employed, among other things, metallic thermal protection systems, and cryogenic fuel tanks for liquid hydrogen.
More specifically, the engine that was utilized, the prototype XRS—2200, was a linear aerospike research engine that included 20 combustion chambers, ten aligned on each end of a ramp center body, which NASA and Rocketdyne developed. Liquid hydrogen and liquid oxygen were used with existing cooling systems—which design choice provided a significant thrust but also imposed certain limitations. See
Other experimental attempts have also failed. For example, attempts to develop an annular aerospike nozzle have not been met with success. Among other things, erosion of the nozzle support, nozzle ablation, and cooling issues have been among the difficulties presented. Accordingly, aerospike technology is more difficult to deploy than conventional engines, which use a bell nozzle because of design, development and fabrication, and other things.
An aerospike engine is an alternative design intended to permit a spacecraft to leave the atmosphere while maintaining thrust efficiency from ground level to the upper reaches of the atmosphere, but it also provides other advantages over traditional bell nozzle designs. Nevertheless, design complexities, reliance upon traditional techniques and conventional fuel types, and limited test data, among other things, have hindered advances in this type of engine.
Accordingly, there has been a long-felt need for an improved rocket engine design that addresses the aforesaid problems and provides a more efficient, effective, lighter, and more cost-effective design.
The instant invention relates to a catalyst system, and in particular a catalyst system adapted for an aerospike rocket engine system. The catalyst system includes a container having a fuel input at one end and, an opening for an exhaust another end. Near the fuel input, a fuel spreader plate is provided which can spread fuel over a catalyst that neither provided in the catalyst chamber within. In addition, an orifice plate is provided after the catalyst to constrain the flow of the expanding of resulting fuel and catalyst. In addition, a supplemental port is provided and connected to a perimeter wall of the catalyst chamber in order to deliver supplemental fuel, oxidizer or catalyst refill into the chamber. Preferably the supplemental port is provided at a downstream end of the catalyst chamber near the orifice plate, at a region where a substantial amount of the fuel and catalyst have already mixed before introduction of the oxidizer.
The catalyst system chamber is designed to provide for convergent flow within the chamber and the expanding mixture exits through the orifice plate, and becomes divergent at an exhaust end of the system.
The catalyst system can also include a thrust ring, which is removably for engine designers to add one or more catalyst packages into the catalyst system from the exhaust end. The thrust ring can be adapted to include connectors to a thruster which can be provided to receive the exhaust from the catalyst, system at its exhaust end.
One particular catalyst for use in the system is alumina foam impregnated with potassium permanganate, which can be combined with fuel such as kerosene, or RP-1, and a further oxidizer such as hydrogen peroxide can be used.
The system can be adapted for modular use, where a number of prepackaged catalyst packages can be provided and packed into the system for dry fueling of the rocket engine. Where multiple catalysts are used, the catalysts are separated to allow upstream catalysts to react before expanding fuel catalyst mixture blows through the system. Separators include nonconsumable materials such as steel, and can also include reactive materials such as platinum, palladium, and silver oxide to supplement the catalyzing of fuel and oxidizer.
Other types of catalyst packages can include sintered ceramic pellets impregnated with potassium permanganate surrounded by wire mesh.
It is to be understood that both the foregoing description and the following description are exemplary and explanatory only and are not restrictive of the invention, as claimed. Specific examples are included in the following description for purposes of clarity, but various details can be changed within the scope of the present invention.
A preferred embodiment of the invention has been chosen for detailed description to enable those having ordinary skill in the art to which the invention pertains to understand how to construct and use the invention readily and is shown in the accompanying drawings in which:
The above-referenced figures are not to scale and are for reference only in assisting the reader in understanding the invention in conjunction with the detailed written description which follows.
A catalyst system according to the invention adapted for an aerospike rocket engine the invention is herein provided, which addresses the drawbacks and inefficiencies that have heretofore hindered the development of this aerospace engine technology.
A significant difficulty in developing an efficient aerospike engine is the complex flow field it provides over varying conditions such as altitude. At low altitudes, the plume structure of the jet exhaust is separated at its base and is called “open wake mode.” For higher altitudes, the converse is true; where the ambient pressure is low, the base flow field becomes closed, closing the wake, where base pressure is constant. See
Referring to the drawings,
In
More specifically, as shown in
An aerospike engine system 500, according to the invention, can also include one or more additional systems, depending on mission requirements, including an intermediate catalyst control system 590 and a fuel and catalyst mixture control system 580, as further described herein. A more detailed description of specific components will follow.
In a preferred embodiment, the system is adapted for use with a fuel such as kerosene or RP-1 and one or more types of oxidizers, such as hydrogen peroxide, and one or more forms of catalysts, such as various forms of potassium permanganate, whether in solid pellet form or in solution. Other catalysts can include platinum, palladium, and silver oxide, which can be provided in various forms such as a screen or mesh. A benefit of such a choice of fuels, oxidizers, and catalysts is safety and cost. These substances can be used at room temperature—avoiding complicated fuel cooling systems—and provide greater safety and simplicity than traditional fuel choices. Traditional fuel sources such as liquid hydrogen and liquid oxygen are highly volatile, reactive, and difficult to maintain.
Accordingly, a fuel system 505 includes at least one fuel container and one or more fuel control valves. The fuel system 505 is operatively connected to the catalyst system 520 to provide a fuel, such as kerosene, to a fuel inlet at one end of the catalyst system 520. In addition, the fuel system may also include a liquid oxidizer, such as hydrogen peroxide, which is operatively connected to the catalyst system 520. The fuel system 505 is controlled by a fuel and catalyst control system 510.
A fuel and catalyst control system 510 can include a device such as a computer or ASIC as can be appreciated by persons of ordinary skill in the art and is operatively connected to the fuel system to control the flow of fuel into the catalyst system 520. The fuel system 505 can also include the electrical, hydraulic, and fuel lines (not shown) such as used by conventional systems, such as electrically controlled flow valves. It can thereby control each individual thruster and any refueling thereof. In addition, a separate catalyst mixer control system 580 can be provided or incorporated as part of the fuel and catalyst control system 510 to provide a specific control system to control the rate of flow of oxidizer/second catalyst. An intermediate catalyst control system 590 can also be provided depending on mission parameters and can be a redundant device such as a computer or ASIC, or a simple electromechanical system operatively connected to the fuel system 505 and catalyst system 520, and controlled by the catalyst mixture control system 580. The system is adapted to differentiate between the control of oxidizer and liquid catalyst that may be introduced through a supplemental liquid catalyst/oxidizer port.
Specifically, the fuel and catalyst mixture control system, can be provided to start, throttle, and shut down fuel entering the catalyst system. In addition, the fuel and catalyst mixture control system fuel can also provide a throttle of each thruster individually. In addition, the catalyst mixture control system 580 can be adapted to control in-flight or in-orbit refueling of the catalyst system.
Shut down and restart, capability of an engine is important for engine design for orientation and or to change, as well as being useful for continuous flight and maneuverability. An engine that has multiple chambers that are individually throttleable can permit thrust vectoring while also being more efficient in space travel. For example, such an engine is helpful to provide a vehicle that cannot only deliver payload but turn, orient, deorbit, as well as reenter the atmosphere on the land. The above engine design flexibility for the choice of fuels and catalysts such as peroxide, kerosene, and potassium permanganate, among others.
One such design includes having liquid oxygen and methane fuel sources and a preferred nozzle design, namely an annular conical isentropic truncated aerospike nozzle. The particular design of this engine can also include bleed compensation for a single stage.
An embodiment of an aerospike engine, according to the invention, can be adapted for other fuel types. For example, an aerospike rocket engine can be provided with two catalysts for the aerospike engine chambers, namely a primary fuel such as liquid hydrogen and a primary oxidizer such as liquid oxygen. Alternatively, other fuels that can be used include methane and peroxide or kerosene. For example, in a further embodiment, the primary oxidizer can be fed from a peroxide generator as part of the main fuel of the fuel system 505, and accordingly, the catalyst system described above is adapted for this purpose.
For both catalysts, other catalytic material could be used in place of potassium permanganate. These include manganese dioxide, palladium, or silver oxide, among others. Other liquid catalysts can also be used.
In a further embodiment, fuel can be introduced to the combustion chamber 560 at a point after the catalyst system 520. (not shown). In such a variation, as the hot gas enters the combustion chamber, it ignites the hydrocarbon fuel automatically without the need for an igniter.
In addition, the fuel and catalyst, mixture control system 580 can be provided to shunt exhaust gas from a catalyst system to power the turbine system 570. The fuel and catalyst mixture control system can also be adapted to control a separate turbine system 574 for use in conjunction with the aerospike engine. It can be appreciated by a person of ordinary skill in the art that contemporary turbine or turbofan systems can be adapted for use with an embodiment aerospike engine according to the invention.
In an embodiment of the invention, the fuel introduced to the catalyst system can be pressure fed. However, it can be appreciated that a gas generator cycle can be provided for the power cycle of a bi-propellant rocket engine, whereby some of the propellants are burned in a gas generator. The resulting hot gas can be used for a turbine system 570 or to power the engine pump while the gas is then exhausted. The fuels enter the combustion chambers, whereupon the combination is ignited, combustion occurs, and the resultant hot gas is then passed through the aerospike nozzle to produce thrust.
An aerospike engine system 500 can also include one or more additional systems, depending on mission requirements, including a second or alternative fuel system, an ignition system, a thermal protection system, a pre-burner, fuel inlet, fuel pump, cryo-control system, and heat exchanger, among other things.
Fabrication of an aerospike engine includes choosing lightweight materials that can perform under the rigors of the rocket engine and can include SiC or SiC composite for the composition of the spike, which has good heat resistant characteristics. Titanium 6-4 also has good, characteristics.
In addition, the cooling of engine parts can be provided by using cooling channels. Other high-performance materials such as organic matrix composition copper alloy (OMC) have been used in combustion chambers, whereas other structural support materials can be fabricated from a stainless-steel alloy.
In a further embodiment, as shown in
In
As shown in
As shown in
It can be appreciated toy a person of skill in the art of aerospike engine design that several parameters play an important role in the design of an aerospike engine. The type of nozzle, whether it is linear, annular, or tile shaped, as well as the nozzle contour, thrust performance factors, and flow field, are important considerations.
An aerospike, according to the invention, utilizes aspects of a plug nozzle and has a conical shape with a curved and pointed spike. The gradual conical base to spike shape allows the exhaust gases to expand through an isentropic or constant entropy process. Accordingly, the nozzle's efficiency is maximized, and little or no energy is lost due to the turbulent mixing of exhaust flow. Theoretically, the curved spike must be of infinite length for ideal implementation, but this is not possible. There is a tradeoff between the form of the exhaust plume and aspects of the physical means of boundary constraint imposed by the spike. It has an inner boundary and can be described as a radial “inflow” type of nozzle, meaning the expansion of the outward flow is towards the nozzle axis. There is also a secondary flow circulation which looks like an aerodynamic spike and thus is named “aerospike.” The choice of spike length is a tradeoff between weight and efficiency.
A preferred embodiment of an aerospike, according to the invention, is partially cut off or truncated. This reduces the weight with a modest decrease in efficiency. The length of the spike and amount of truncation depends on the base pressure, i.e., the pressure generated by the exhaust flow over the base and the timing or transition of the closed wake from the exhaust flow.
In alternative embodiments, the exhaust control spike can also be provided with a throat insert and spike rod. Portions of the exhaust control spike 540, such as the spike rod and throat insert, if provided, can be manufactured out of graphite.
As shown in the conceptual drawing of
In other words, the nozzle ramp of the aerospike nozzle is equivalent to the bell nozzle's inner wall, and atmospheric pressure acts as the outer wall. The combustion gasses parallel to the nozzle ramp and the atmospheric pressure work together to produce thrust. The efficiency behind the aerospike nozzle is due to the exhaust recirculating near the base of the spike and raising the pressure in that area to almost the equivalent of the surrounding pressure. As a result, the exhaust virtually offsets the aerodynamic forces acting on the rocket. Thus, the rocket engine does not lose thrust.
With reference to the embodiment of the invention shown in
The design of the cell nozzle affects the performance of the engine. The throat of the cell nozzle should be such that it boosts the velocity of the flow to a sonic speed, and thereafter expansion further increases its velocity. The heat load on the throat area can be significant. The exit of the cell nozzle should contour to permit the flow exiting to flow smoothly over the surface of the aerospike without creating disturbance and or eddies. In addition, the gaps between adjacent cell nozzles should be maintained at a minimum to avoid turbulence and differential effects. In one embodiment, the cell nozzles are preferably fabricated with titanium (TI-6-4) and Molybdenum alloy as a high-temperature materials. Other portions of the ceil nozzles and injectors of the catalyst system 520 can be made of aluminum alloy, and an outer combustion chamber can be provided with steel and lined with an ablative liner made out of silk fibers, phenolic resin, and/or phenolic glass. Additionally, the thruster can include a silicon/phenolic ablative liner.
A spreader plate 522 can be provided to distribute fuel that has been received by the catalyst system to areas of the internal catalyst system chamber 1110 containing one or more catalysts. One embodiment of a spreader plate, according to the invention, is a solid plate having a pattern of apertures extending through the plate through which the fuel can pass. In one embodiment, the spreader plate has a repeating pattern of 128 holes of 0.065 diameter mm evenly spread around the perimeter or within a grid. Beneath the spreader plate and within the catalyst system 520, one or more catalysts or modular catalyst packages can be provided, such as potassium permanganate provided in pellet form. The catalyst system 520 also includes a supplemental port 1101 to distribute an oxidizer within the catalyst system 520 at an intermediate region of the catalyst chamber and preferably proximate to the orifice plate. For example, the supplemental port 1101 can be a ring tube connected at one end for fluid connection to the catalyst mixture control system 580 at one end and having at least one aperture which provides for the flow of oxidizer or catalyst at a perimeter into the chamber. Preferably, the supplemental port 1101 distributes an oxidizer, such as hydrogen peroxide, at a point after the first catalyst has been mixed with the fuel and above the orifice plate 524 or thrust ring 526. It can be appreciated by that the supplemental port 2101 can be connected to the fuel system 505 and can receive an oxidizer (or catalyst for refueling) by being operatively connected to the fuel and catalyst control system 510 to control the flow of the oxidizer, such as concentrated hydrogen peroxide.
In an alternative embodiment, the supplemental port 1101 provides an additional catalyst for refueling the catalyst chamber.
The orifice plate 524 is provided to create a convergent-divergent section within the catalyst system but just prior to exhaust to the combustion chamber. In one embodiment, the orifice plate is provided as a solid plate having several apertures there through. The apertures are arranged radially from the center of the orifice plate 524 and can have an elongated form. The radial pattern from perimeter to center promotes flow from the convergent to the divergent exhaust region. Accordingly, the orifice plate provides a constricting flow of the fuel catalyst mixture as an expanding gas and allows that mixture to pass through the apertures to a divergent region following the orifice plate more effectively.
The thrust ring 526 is provided for further directing the resulting expanding gas-fuel-catalyst mixture to a combustion chamber 560. The thrust ring 526 can also provide a connection from the catalyst system 520 to the thruster 530. More particularly, the thrust ring allows a modular catalyst system 520 to be added to an existing thruster for a reusable system.
It can be appreciated by a person of ordinary skill in the art that various embodiments of the invention can be provided where one or more of the flow constriction devices can be disposed in different areas. For example, in one embodiment shown in
As described above, an oxidizer, such as hydrogen peroxide, can be provided through a supplemental port 1101 disposed between the orifice plate 524 and spreader plate 522, and provide the fuel into the internal catalyst system chamber 1110.
Alternatively, a catalyst, such as potassium permanganate, as described above, can be provided through the supplemental port 1101 for initial filling or refueling. Accordingly, such further embodiments of the invention are advantageous for single-stage to orbit vehicles and reusable craft. Furthermore, various fuel choices are permitted, allowing for vehicles intended for multiple uses and inflight or in-orbit refueling, as described further below.
Several alternative embodiments of a catalyst system 520 having more than one catalyst are provided. A benefit of these arrangements is to provide the engine designer with the flexibility of packaging catalyst sources to satisfy various mission parameters and can be designed as a bipropellant or monopropellant system.
In one embodiment, as shown in
A supplemental oxidizer or catalyst in liquid form, such as concentrated hydrogen peroxide, can be provided to mix with the resulting mixture of fuel and the at least one first catalyst within the chamber. The supplemental oxidizer or catalyst can be introduced via a supplemental port 1101 either at an intermediate region of the chamber 1110 or at or near the bottom thereof.
In a preferred embodiment, the at least one first catalyst is provided as a monolithic alumina foam (aluminum oxide) which can be impregnated with a catalyst such as potassium permanganate. Upon complete reaction, such material may be expected to be consumed. This system allows for a single monolithic catalyst without requiring integrity screens, such as a separator 1410. Alternatively, the first catalyst could include a non-consumable catalyst that can react with the fuel. Such a non-consumable catalyst can include a wire mesh of steel, platinum, palladium, or silver oxide, or a combination of these metals. Alternatively, a matrix of porous or hollow pellets comprised of such metal can be used.
In addition, the first catalyst could include a nonreactive matrix, such as a monolithic alumina foam, and initially be provided with a consumable first catalyst. Once the first catalyst is consumed, an additional first catalyst, can be provided through a supplemental port 1101 to refuel the chamber. Catalysts can also be comprised of aluminum oxide ceramic pellets saturated with potassium permanganate (sintered) and may be preferable for different embodiments of the invention. These ceramic pellets can be baked to embed the potassium permanganate in an alumina matrix. It can be appreciated by a person of ordinary skill in the art that appropriate catalyst and fuel combinations require different forms and quantities depending on the choice of fuel and catalyst, and as may be required by various mission parameters.
In a further alternative embodiment, as shown in
Additional porous separators 1410, such as finer steel mesh, are provided between each catalyst package 1250. In the embodiment shown in
Alternatively, at least one of the separators 1410 can provide flow constriction by providing a finer grade mesh grid to constrict the flow of fuel and or fuel/catalyst mixture. For example, the separator 1410 at the bottom or exit end of the chamber 1110 can provide flow restriction in lieu of requiring an additional spreader plate 522 or orifice plate 524.
As before, an oxidizer or supplemental catalyst in liquid form can be introduced into the chamber 1110 at an intermediate point or at or near the bottom of the chamber.
In an alternative embodiment, at least one of the separators is provided as a mesh of a metallic catalyst—such as silver or platinum—which reacts with the second or supplemental catalyst or oxidizer, such as hydrogen peroxide, thereby ensuring complete reaction and efficient use of fuel and catalyst materials.
A spreader plate 522 (such as shown in
In the embodiment shown in
As shown in
Such an embodiment can be described as a bi-propellant system when used in conjunction with a liquid catalyst or oxidizer introduced through a supplemental port 1101.
Thus, the combined use of separators—including flow restrictors such as a spreader plate, orifice plate, thrust ring, and/or stainless steel screens—can be provided not only for separating various catalysts in the catalyst system and control the rate of the decomposition of catalyst but can also provide flexibility of design of the catalyst system 520 to obtain the benefit of convergent and divergent regions of combustion within the catalyst system 520 and exhaust to the combustion chamber 560 of the thruster.
The fuel and catalyst mixture control system 580 and intermediate catalyst control system 590, as described above, can be used to implement a variety of controlled combustion within the catalyst system 520 and thruster unit. For example, it can be appreciated by a person of ordinary skill in the art that the fuel and catalyst mixer control system 580 as well as intermediate catalyst control system 590 are adapted to control the rate of flow of fuel and any liquid catalysts through any supplemental port that may be provided. More specifically, the fuel and catalyst mixture control system 580 provides a carefully metered flow of fuel, such as RP-1, into the chamber for mixing with catalyst (such as potassium permanganate) at a rate that avoids flooding, explosive decomposition, or blockage and allows sufficient mixing of fuel and catalyst. In addition, the fuel and catalyst mixture control system 580 accounts for the addition of oxidizer provided to the mixture at a rate that accounts for the reaction of the mixture.
With respect to the embodiment shown in
For example, as shown in
Each separate region can be provided initially with one or more catalysts 1220, or remain empty, or be tillable with one or more catalysts from one or more supplemental catalyst ports 1101. Tor example, a first region 1501 can be fillable with a liquid from a supplemental catalyst port 1101, which, when it sets, provides a foam matrix for receiving fuel or catalyst. In this manner, the embodiment shown in
In one embodiment, three separators 1410 can be provided in a static, fixed position and thereby provide three empty regions for fuel/catalyst, through the catalyst system. For example, similar to
In an alternative embodiment, the separator 1410 can be provided as a consumable mesh that degrades gradually as the first catalyst/fuel mixture is consumed, rather than a fixed non-consumable steel mesh.
In an alternative embodiment shown in
In addition, downstream separators can be provided with a finer mesh than upstream separators, i.e., the holes of the mesh are smaller to catch the smaller pellets as they arc consumed so they do not blow through the system and can be fully utilized.
In addition, a supplemental catalyst port 1101 is shown provided as a ring conduit for the distribution of supplemental catalyst around the perimeter of the catalyst system chamber 1110, and has apertures (not shown) periodically spaced around the perimeter for the flow of supplemental catalyst into the chamber.
The fuels adaptable for engines that are potentially runway safe can be adapted utilizing existing commercial airline technology, wherein alternative embodiments of the existing invention can be designed having a scale to replace conventional turbofan engines.
Additional fuel distribution and control components can be provided in alternative embodiments of the invention. The fuel and catalyst mixture system 580 introduces fuel into the catalyst system, either at a top portion (as described above) or into intermediate sections of the catalyst system. In addition, the intermediate catalyst control system 590 can provide for effectively mixing fuel and catalyst in a predetermined sequence, controlling the fuel and catalyst mixture system 580. It can be appreciated by persons of ordinary skill in the art that electrical, hydraulic, valves, and fuel lines can be provided for the above-described intermediate catalyst control systems and catalyst mixture systems.
Aspects of the embodiments described herein can be modified within the scope of the invention in order to adapt an embodiment of the catalyst system and aerospike engine to suit different purposes and under different conditions.
Various changes may be made to the system and process embodying the principles of the invention. The foregoing embodiments are set forth in an illustrative and not in a limiting sense. The scope of the invention is defined by the claims appended hereto.
This continuation-in-part application claims priority to U.S. patent application Ser. No. 16/457,813 filed Jun. 28, 2019, which claims the benefit of U.S. Provisional Application Ser. No. 62/691,839, having a filing date of Jun. 29, 2018, the entire contents of which are all relied upon and fully incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62691839 | Jun 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16457813 | Jun 2019 | US |
| Child | 17845811 | US |
