Patent Publication Number: US-11384816-B2

Title: Gearbox with internal diaphragm

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. 
     BACKGROUND 
     Field of the Invention 
     The present invention relates generally to the field of driveline components, for example driveline components used in irrigation systems. 
     Description of the Related Art 
     Worm wheel gearboxes have a worm gear that engages a bull gear. Such gearboxes are especially useful where low speed and high torque is desirable. Often, the worm gear is disposed on an input or drive shaft and the bull gear is linked to an output shaft. The gearbox can also be sealed. These worm wheel gearboxes are commonly used, for example, in agricultural irrigation systems and potato pilers. 
     Irrigation systems are widely used throughout the world to provide water for agricultural purposes in arid regions. Such systems include center pivot irrigation and lateral move systems. Typically, such systems include a series of spaced apart support towers connected by truss sections that support an elevated water distribution pipe between the towers. The trusses are linked together, enabling such irrigation systems to stretch to lengths of a thousand yards or more. In center pivot systems, the water distribution pipe extends radially from a central pivot communicating with a pressurized water supply. In lateral or linear move irrigation systems, the water distribution pipe extends laterally from a canal feed or hose drag system that provides a pressurized water supply. 
     Water passing through the distribution pipe is forced out through a number of sprinkler heads, spray guns, drop nozzles, and the like, spaced along the length of the pipe. Each tower in the system is supported on wheels that are driven at low speeds to move the tower in a circular path about the central pivot, or a linear path in the case of lateral move systems, to thereby irrigate a tract of land. 
     A number of drive assemblies have been developed for driving the support wheels of sprinkler irrigation systems. The most common drive assembly includes an electric motor connected to a center gear drive assembly, a first wheel gear assembly coupled to the center gear drive assembly by a first drive shaft, and a second wheel gear assembly coupled to the opposite side of the center gear drive assembly by a second drive shaft. Each of the first and second drive shafts typically has a driveline coupler at each end that allows the shafts to be quickly and easily pulled apart and put back together to facilitate field maintenance and/or towing from field to field. 
     The wheel gear assemblies generally include a wheel connected to a gearbox. The gearbox can be a sealed worm wheel gearbox that is provided having a worm disposed on a driveshaft. The worm engages a bull gear within the gearbox. The motor can drive a shaft which acts as the input shaft to the worm wheel gearbox. The bull gear is linked to an output shaft. The output shaft has an output flange which connects to the driven wheel. Rotation of the input shaft is thus transmitted via the gearbox to the output shaft, driving the wheels of the irrigation system. 
     A typical irrigation watering system has a number of such support wheels and each wheel or pair of wheels typically is driven by a motor and worm wheel gearbox as described. Worm wheel gearboxes are especially advantageous in this environment because once the drive motor stops, the worm and bull gear combination allow very little additional movement such as coasting. Thus, the irrigation system will remain in its position even if it is on a hill or other unlevel surface. 
     The farm environment tends to be wet, muddy, silty, and dusty. Thus, these gearboxes are generally sealed to prevent contamination of the gearbox contents, such as the oil contained therein. 
     Worm wheel gearboxes are also commonly used in potato pilers. A potato piler comprises a conveyor disposed on a wheeled frame. To enable even piling of potatoes, the conveyor must be moved short, precise distances during operation. Potato pilers thus typically comprise a motor which rotatably drives a shaft and a worm wheel gearbox that transmits the shaft rotation to drive the wheels of the potato piler. This enables the potato piler to be moved short, precise distances when piling potatoes. 
     SUMMARY 
     There exists a continuing need to provide improvements in gearboxes and in worm wheel gearboxes. For example, there exists a need to improve the ability of gearboxes to appropriately deal with changes in temperature and internal pressure. Proper seals should be maintained to prevent contamination of the gearbox contents. 
     Some embodiments of a gearbox for an irrigation system can comprise a housing, a worm gear within the housing, a bull gear within the housing and configured to be engaged with the worm gear, a diaphragm, and a vent. The diaphragm can define a chamber configured for expansion and contraction and configured to be positioned inside the housing to relieve pressure build-up within the housing. The vent can be configured to allow air to flow between the atmosphere and the chamber. 
     There also exists a need to introduce sensors into gearboxes in a reliable way that will not cause the gearbox to leak oil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates part of an irrigation system with a drive assembly. 
         FIG. 1B  shows part of a drive assembly with a center drive, wheel gearboxes, drive shafts, and driveline couplers. 
         FIG. 2  illustrates an embodiment of a wheel gearbox. 
         FIG. 3  illustrates a cross section of the gearbox of  FIG. 2 . 
         FIG. 4A  illustrates a partially exploded view of the embodiment of the wheel gearbox. 
         FIG. 4B  illustrates a subassembly of the gearbox cover. 
         FIG. 5  is an assembled side view of the gearbox of  FIG. 2 . 
         FIG. 6  is an assembled end view of the gearbox of  FIG. 2 . 
         FIG. 7  illustrates another embodiment of a wheel gearbox. 
         FIG. 8  illustrates a cross section of the gearbox of  FIG. 7 . 
         FIG. 9  is an assembled side view of the gearbox of  FIG. 7 . 
         FIG. 10  is an assembled end view of the gearbox of  FIG. 7 . 
         FIG. 11A  illustrates an another embodiment of a flange for securing a diaphragm to the gearbox cover. 
         FIG. 11B  illustrates a cross section of another embodiment of the gearbox with the flange of  FIG. 11A . 
         FIGS. 12A-12E  illustrate embodiments of diaphragms. 
     
    
    
     DETAILED DESCRIPTION 
     An irrigation system  1  for providing water for agricultural purposes and as partially shown in  FIG. 1A , can have a water piping and delivery system  2  and a drive assembly  4 . An embodiment of a drive assembly  4  is shown in more detail in  FIG. 1B . A drive assembly  4  can have a center drive  3 , a wheel gearbox  10 , a shaft or drive shaft  8  and one or more driveline couplers  11 . A center drive  3  can have motor  5  connected to a gearbox  6  to deliver a torque to a drive shaft  8 . Driveline couplers  11  are shown connecting the drive shafts or shafts  7 ,  9  of the gearboxes  10  and center drive  3  to the drive shafts  8 . Drive shafts  8  typically have a driveline coupler  11  at each end to allow the shafts  8  to be quickly and easily pulled apart and put back together to facilitate field maintenance and/or towing from field to field. 
     In use, hub  14  on the gearbox  10  can connect with a wheel. The center drive  3  can drive the drive shaft  8  which in turn can drive the gearbox  10 . The gearbox  10  can transfer the motion of the turning drive shaft  8  into a rotational motion at the hub  14  to turn the wheel and drive an irrigation system  1 . The gearbox  10  can be either non-towable or towable. The wheel gearbox  10  can have a handle (not shown) that can be used to disengage the gears inside the gearbox to allow free rotation of the hub  14 . Alternatively, the wheel gearbox could be fitted with a towable hub. 
     In a towable state, a driveline coupler  11  can be separated so that the wheel gearbox  10  can be rotated or pivoted to a new orientation. Also, the handle can be used to disengage the gears inside the wheel gearbox  10 . In this state, the wheel gearbox  10  is no longer connected to the center drive  6  and is free to rotate. In a typical operation a farmer or user can attach a system  1  in a towable state to a tractor or truck and tow the system to a new location, such as to a different field. Examples of a towable wheel gearbox can be found in U.S. Pat. No. 6,237,863, entitled “Disengageable Worm Wheel Gearbox,” which is incorporated herein by reference in its entirety and made a part of this specification. 
     Referring next to  FIGS. 2-6 , a worm wheel gearbox  10  is shown in more detail. The worm wheel gearbox  10  preferably comprises a gearbox housing  12 , a driveshaft  7  having a worm gear  16  disposed thereon, and a bull gear  18  in driving relation with an output shaft  20 . The worm gear  16  engages the bull gear  18  within the gearbox housing  12 . The output shaft  20  is connected to an output flange or hub  14  which can be attached to a wheel. 
     The bull gear  18  and output shaft  20  are arranged in the gearbox housing  12  to provide for transfer of torque. A gearbox cover  22  is attached to the housing  12 . The worm wheel gearbox  10  can also include various other components, such as bearings  76 , bearing cups, shims, spacers, o-rings, seals  30 , gaskets, etc. 
     A gear oil bath can lubricate the contents of the gearbox  10 . For example, the gearbox  10  can be substantially full of oil. In other embodiments, the gearbox  10  can be less than full of oil, i.e. 10-90%, 25-75%, or 50% full. In some embodiments, the gearbox  10  can have an air gap, such as a 1 inch air gap. It can be beneficial to reduce or eliminate the air gap inside the gearbox to reduce the possibility of condensation within the gearbox. The gearbox can hold a predetermined amount of oil, such as 1 gallon or 4 quarts of oil. Other embodiments can hold more or less than this, such as 3 quarts, 5 quarts, and 8 quarts. As mentioned, the predetermined amount of oil can substantially fill the gearbox or leave an air gap. 
     The gearbox  10  can include a drain plug  26  and a fill plug  28 . The fill plug  28  can be used to add a lubricant, such as oil, into the gearbox  10 . The drain plug  26  can be used to drain some or all of the lubricant, or other liquids, such as water, from the gearbox  10 . It can be undesirable to allow water, such as the water from condensation, to build up within the gearbox  10 . The drain plug  26  can be used to drain this water. It can also be used, for example, to change the oil. 
     The drive assembly  4 , and therefore the gearbox  10 , is often used in a dirty and corrosive environment. As discussed, a gearbox  10  can be used on irrigation equipment  1  in fields to provide water to crops and the like. In this environment, the gearbox  10  can be exposed to the elements for extended periods of time. The irrigation equipment  1  can travel through dirt and rocks and the gearbox  10  can likewise be affected by these elements. The irrigation equipment  1  itself can be constantly wet as water is provided to the field. Also, irrigation equipment  1  is often used in hot climates. Thus, a gearbox  10  can be exposed to direct sunlight, and constantly wetted and then dried by the sun. In addition, the mornings and nights can be very cold. These conditions can be highly corrosive to the irrigation equipment  1  and can expose the components to extreme fluctuations in temperature and other conditions. 
     The gearbox  10  is generally sealed. This allows the gearbox  10  to be used in corrosive environments while limiting the impact of the environment on the internal components. For example, the various seals and gaskets on the gearbox can block water and contaminants from entering the gearbox, thus maintaining the gearbox in better condition and requiring fewer oil changes and other maintenance then may otherwise be required. 
     In addition to the outside conditions experienced by the gearbox  10 , during use the internal gear oil may become hot and expand. This can increase the oil pressure. At other times, the gear oil may cool and contract, decreasing the oil pressure. For example, in many cities of the United States it is typical for the average difference between the high and low temperature of a typical summer day to be around 20-30° F. Other factors, such as rainfall, shade, direct sunlight, amount of use, etc. can increase the range of temperatures that a gearbox may experience in a day. Thus, during the course of a day, the gearbox can experience extreme swings in temperature and pressure. It has been found that this increased oil pressure can cause the seals  30  around the drive shaft and output shaft to fail, or to have a shortened life span therefore requiring early replacement. The pressure inside the gearbox has been found to increase by 5-7 psi which can force the seals against the drive shaft, causing the seals to wear faster due to the additional force. Not only do the seals have to be replaced earlier but oil can leak out of the gearbox because of the increased pressure. 
     An expansion chamber  50  can be provided to regulate the internal change of pressure. An elastomeric diaphragm  36  (e.g., rubber) can be used to create an expansion chamber within the gearbox  10 . The expansion chamber  50  can help to prevent the seals  30 ,  32  from failing and the oil from leaking out of the gearbox. The diaphragm  36  can expand or contract to relieve changes in internal pressure. For example, when the gear oil becomes hot the oil expands, increasing the internal pressure. The diaphragm  36  can then also expand to relieve the pressure and reduce the stress on other components, such as seals and gaskets. The diaphragm  36  can be exposed to the atmosphere on the expansion chamber side and exposed to the internal pressure of the gearbox  10  on the other side. This can allow the diaphragm  36  to normalize the internal pressure of the gearbox  10  with atmospheric pressure. 
     The expansion chamber  50  can expose the diaphragm  36  to the atmosphere through a vent  48  or some other feature so as to not create a sealed chamber around the diaphragm  36 . The diaphragm  36  can be used to relieve internal pressure in the gearbox  10  by expanding or contracting in response to a change in pressure inside the gearbox  10 . The movement of the diaphragm can change the size of the chamber  50 . The chamber  50  can expand or contract in one or more directions to normalize the pressure inside the gearbox  10  with the pressure outside the gearbox  10 . 
     Having the diaphragm  36  or other expansion chamber inside the gearbox can provide certain benefits. For example, an elastomeric diaphragm can sit in a bath of gear oil which can increase the flexibility and the life of the diaphragm. Having the expansion chamber inside the gearbox does not require a separate cover to protect the expansion chamber. The gearbox cover  22  itself can cover and protect the expansion chamber. The expansion chamber  50  can be used to seal or otherwise separate the working portion of the gearbox  10  from the atmosphere. In some embodiments, the gearbox housing  12  can be completely filled with oil in order to reduce the chance that air is present within the working portion of the gearbox housing  12 . Generally, fluctuations in temperature can result in the formation of water within gearbox housing  12 , which can be detrimental to the operation of the gearbox  10 . In some instances, the gearbox can be filled up such that all of the airspace is eliminated. By eliminating the airspace, the chance of water contamination of the oil is greatly reduced, which can extend the useful life of the oil and the gearbox. The expansion chamber  50  can contract and expand based on the operating conditions of the gearbox. The formation of water can be largely confined to the expansion chamber  50 . The expansion chamber  50  can have a vent  48  regulate the pressure and an outlet port  54  to drain fluids, such as water, that can form during operation of the gearbox  10 . The outlet port  54  can be used to inspect for oil and/or water within the expansion chamber  50  during usage of the gear box. The outlet port  54  can be used as a pressure relief during production to test to help prevent other vents from being blown out during testing. In some embodiments, the gearbox  10  may not include an outlet port  54 . 
     The diaphragm  36  can be configured to be positioned inside the gearbox  10  and to relieve pressure build-up within the gearbox  10  caused from changes in temperature and the related thermal expansion or contraction of a volume of oil configured to be held within the outer casing. It has been found in testing that a gearbox without pressure relief experienced an increase of 6 psi with an oil temperature rise of 60.5 degrees F. A gearbox  10  with a diaphragm  36  under the same testing conditions experienced a reduced increase in pressure. 
     With reference again to  FIG. 3 , one method of positioning the diaphragm  36  inside the gearbox is shown. The diaphragm  36  can be positioned to be offset from the bull gear  18  or any other moving parts, such as the output shaft  20 , so that it can expand and contract away from the moving parts. A flange  41  can help secure the diaphragm  36  to a back side of the gearbox cover  22 . The gearbox cover  22  can also include an outer channel or groove  23  and an inner channel or groove  24 . The channels  23 ,  24  extend circumferentially about the gearbox cover  22 . 
     The diaphragm  36  or other type of device can be one of many different devices that can expand and contract in response to a pressure change. The diaphragm can be any of multiple shapes and sizes and can be connected to the gearbox  10  in many different ways. In the illustrated embodiment, the diaphragm  36  is substantially circular is positioned circumferentially around the output shaft  20 . The diaphragm  36  completely encircles the output shaft  20 . In some embodiments, the diaphragm  36  may only partially encircle the output shaft. For example, the diaphragm  36  may encircle less than 360 degrees, less than or equal to 270 degrees, less than or equal to 180 degrees, or less than or equal to 90 degrees of the output shaft  20 . In some embodiments, the diaphragm may be divided up into multiple sections such that the diaphragm is not a single contiguous piece of material. The gearbox  10  may include multiple diaphragm sections that encircle the output shaft with gaps between each section. In some embodiments the diaphragm may have a non-circular configuration. For example, the diaphragm  36  may be sized and shaped to fit within portions or channels of the gearbox cover  22 . 
     In the illustrated embodiment, the diaphragm  36  has a wavy or undulating portion  37 , engagement portions  38   a - b , and a flap  39 . As will be described in further detail below with respect to  FIG. 12 , the undulating portion  37  may be any shape or configuration. In some embodiments, the undulating section may be replaced by a flat section. The engagement portions  38   a - b  can be rounded protrusions that extend outward from the diaphragm and are sized and shaped to engage channels  23  and  24 . The outer engagement portion  38   a  is configured to be positioned within the outer channel  23  and the inner engagement portion  38   b  is configured to be positioned within the inner channel  24 . The engagement portions  38   a - b  can function as positioning and sealing elements to help position and seal the diaphragm within the gearbox cover  22 . The diaphragm flap  39  can be sized and shaped to help secure the diaphragm  36  to the gearbox cover. The flap  39  can include a plurality of orifices that can be used to secure the flange  41  over the diaphragm flap and to the gearbox cover  22 . With additional reference to  FIG. 4B  illustrates a view of a partial assembly of the gearbox cover  22  with the flange  41  securing the diaphragm to the gearbox cover. 
     The diaphragm  36  is configured to seal the expansion chamber  50  from the inside of the gearbox. The flap  39 , flange  41 , inner engagement portion  38   b , and inner channel  24  can help to substantially seal the inner portion of the diaphragm  36 . When the gearbox is assembled, the outer engagement portion  38   a , which is positioned within the outer channel  23 , is sandwiched between the gearbox housing  12  and the gearbox cover  22 , which substantially seals the outer edge of the diaphragm. The outer seal can also help prevent oil from leaking out of the gearbox housing  12  at the seam between the housing and the cover  22 . 
     The diaphragm prevents the air and/or water that accumulates within the expansion chamber from contaminating the oil within the gearbox housing  12 . The diaphragm  36  is also positioned so that it will not expand or contract into any moving parts or be drawn into them. The position of the diaphragm  36  in  FIG. 3  can illustrate a default, empty, or first configuration. The presence of oil or other lubricant can increase the pressure inside the housing and cause the diaphragm to contract or move away from the bull gear  18  to a second configuration. As the temperature and pressure increases or decreases, the diaphragm can assume other contracted or expanded positions. 
     In some instances it has been found that a diaphragm can be forced to move towards a worm gear or other moving part when it is facing the gear or part. For example, in cold conditions a vacuum can be created as the worm gear rotates. This vacuum can cause a diaphragm to move towards the worm gear. This undesirable effect can prevent the diaphragm from functioning properly. The diaphragm can be positioned at defined distances from moving parts, such as the bull gear  18  and output shaft  20 , in order to prevent undesirable effects caused by movement of the diaphragm within the gearbox. 
     The chamber  50 , formed by the diaphragm  36  and the gearbox cover  22  can be vented to the outside through a vent  48 . This can allow the expansion chamber  50  to be inside the gearbox  10  and yet exposed to the outside atmosphere and properly compensate for a change in pressure within the gearbox  10 . Though not readily apparent from the figures, the expansion chamber  50  can be a contiguous chamber that completely encircles the output shaft  20 . The chamber can have a substantially uniform cross sectional size and shape, such as illustrated by the portions of the chamber  20  illustrated in  FIG. 3 . In some embodiments, the cross sectional shape of the chamber may vary within the gearbox. In some embodiments, the expansion chamber may be divided into plurality of isolated sections with each section having a separate vent. 
     The vent  48  can take many forms. For example, the vent  48  can have a filter  56  and a cap  58 . From the chamber  50 , air can flow through the vent, then through the filter  56  into the cap  58  and then out into the atmosphere. 
     The vent  48  can be configured in such as way as to allow air flow through the channels and substantially prevent other flows such as water, mud, etc. through the vent. For example, configuring the vent to have a tortuous path can help prevent water and other material from entering the vent  48  and the chamber  50 . In addition, a filter  56  can further help prevent material from entering the chamber  50 . An example filter  56  is a screw-in vent with internal filter labeled as a POV/metal vent, available from W. L. Gore &amp; Associates, of Newark, Del. In addition a cap  58  can be used to cover the filter  56 , to protect it and to add additional turns in the vent path. 
       FIGS. 7-10  illustrate an alternative embodiment of the gearbox  10 ′ that includes different embodiments of the vent  48 ′ and outlet port  54 ′. The gearbox operates as described above. In the illustrated embodiment, the vent  48 ′ and the outlet port  54 ′ extend outwards through the gearbox cover  22 ′ and are substantially parallel to the output shaft  20 . 
       FIGS. 11A and 11B  illustrates an another embodiment of a flange  141  for securing a diaphragm  136  to the gearbox cover  122 . In the illustrated embodiment, the flange  141  can include an inner portion  142 , arm portions  144 , and an outer portion  146 . The arm portions  144  connect the inner portion  142  and the outer portion  146 . The flange can be formed from multiple pieces or a single piece of material and can include a plurality of holes or orifices for securing the flange  141  to the gearbox cover  122 . The flange  141  is configured to form sections  148 A-D, also referred to as expansion zones  148 . The illustrated embodiment includes four sections. Other embodiments can have any number of sections, different orientations, each section can be uniformly shaped and sized, and/or have different shapes and sizes. The diaphragm  136  can be configured to be sandwiched between the flange  141  and the gearbox cover  122 . 
     The flange  141  can be configured to help support the diaphragm  136  and limit travel of the diaphragm  136  during expansion and contraction. The divisions of the diaphragm  136  into expansion zones help isolate each zone and control the amount of travel of the diaphragm  136  within the zone. Various factors can help to control the amount of travel of the diaphragm, such as the shape of the flange, the size, shape, and configuration of the diaphragm in each zone, the material, and/or other factors. Each zone  148  of the diaphragm  136  can have a defined shape. An example embodiment of a zone  148  of the diaphragm  136  is illustrated in  FIG. 12A .  FIGS. 12B-12E  illustrated various embodiments cross sectional shapes of the diaphragm. An expansion zone of the diaphragm can have any cross sectional shape or configuration. In some embodiments, the diaphragm  140  can be flat. 
     Additionally, the flange  141  can help to improve assembly of the gearbox. The flange  141  can be configured to seal the expansion chamber  50  within the gearbox cover  122  independent of the gearbox housing  12 . The flange  141  can mount directly on the gearbox cover and does not need to come in contact with the housing. This can provide for a modular assembly of the gearbox  10  where the gearbox cover can be assembled and tested without requiring attachment of the housing  12 . 
     In certain embodiments, the gearbox  10  can further include one or more sensor ports (not shown). A sensor can be positioned within the sensor port. In some embodiments, when the sensor port is not in use by a sensor, the port can be capped off or plugged. It may be desired to have certain sensors in certain gearboxes in an irrigation system while other gearboxes do not have sensors or have different sensors. 
     The sensor(s) can comprise at least one of any number of sensors including sensors to measure or detect: temperature, oil level, moisture, pressure, conductivity, etc. A temperature sensor can measure the temperature within the gearbox, for example the temperature of the gear oil within the gearbox. An oil level sensor can measure the level of the oil within the gearbox. A moisture sensor or hydrometer can detect the presence of moisture, or water within the gearbox. A conductivity sensor can detect the presence of metal shavings. These sensors can also be used for other purposes and other sensors can be used for these same and for different purposes. According to certain embodiments, the sensors are oil compatible and can operate in temperature ranges between 30-180 degrees F. 
     In some embodiments, the sensor can be configured to transmit information by wire or wirelessly. For example, a transmitter can be located on or near the gearbox  10 . The transmitter can receive information from the sensor. This information can be transmitted from the transmitter periodically or on a real time basis to a receiver or central computer or monitor and can be transmitted via wires, radio wave, cell phone, etc. The transmitter and/or the sensors can be powered through various methods including electrical connections, battery, generator, etc. 
     The sensor can be connected with wires or wirelessly to a computer control. The computer control can display, relay, or store information from the sensor for present or future use. The control can be part of the gearbox or a separate unit. For example, on a central pivot irrigation system, a control can be located at the pivot which can collect information from one or more sensors, from one or more gearboxes on the system. In some embodiments, a monitoring system can be established to enable a user, such as a farmer to monitor the information from the sensors at a central location independent of the location of the sensors. The monitoring system can interact with the control(s) or it may interact directly with the sensor(s). 
     Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements, and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include these features, elements, and/or states. 
     Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z. 
     While the above detailed description may have shown, described, and pointed out novel features as applied to various embodiments, it may be understood that various omissions, substitutions, and/or changes in the form and details of any particular embodiment may be made without departing from the spirit of the disclosure. As may be recognized, certain embodiments may be embodied within a form that does not provide all of the features and benefits set forth herein, as some features may be used or practiced separately from others. 
     Additionally, features described in connection with one embodiment can be incorporated into another of the disclosed embodiments, even if not expressly discussed herein, and embodiments having the combination of features still fall within the scope of the disclosure. For example, features described above in connection with one embodiment can be used with a different embodiment described herein and the combination still fall within the scope of the disclosure. 
     It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above. Accordingly, unless otherwise stated, or unless clearly incompatible, each embodiment of this disclosure may comprise, additional to its essential features described herein, one or more features as described herein from each other embodiment disclosed herein. 
     Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination. 
     Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. 
     Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. 
     For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, 0.1 degree, or otherwise. 
     The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”. 
     Reference to any prior art in this description is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavor in any country in the world. 
     The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the description of the application, individually or collectively, in any or all combinations of two or more of said parts, elements, or features. 
     Where, in the foregoing description, reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth. In addition, where the term “substantially” or any of its variants have been used as a word of approximation adjacent to a numerical value or range, it is intended to provide sufficient flexibility in the adjacent numerical value or range that encompasses standard manufacturing tolerances and/or rounding to the next significant figure, whichever is greater. 
     It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. For instance, various components may be repositioned as desired. It is therefore intended that such changes and modifications be included within the scope of the invention. Moreover, not all of the features, aspects, and advantages are necessarily required to practice the present invention. Accordingly, the scope of the present invention is intended to be defined only by the claims.