Main valve with grooved rigid internal structure

Disclosed is a main valve for a hydrant including an internal rigid structure including a top surface, a bottom surface, and a locating feature, the locating feature defined in a one of the top surface and the bottom surface; and an outer shell at least partially enclosing the internal rigid structure and interacting with the locating feature.

TECHNICAL FIELD

This disclosure relates to valves. More specifically, this disclosure relates to main valves in a hydrant.

BACKGROUND

Valve elements are used to regulate or control the flow of material by opening, closing, or partially obstructing various passageways. One type of valve or valve element is a main valve, which can be used in a number of applications, such as within a hydrant shoe of a dry-barrel fire hydrant. Main valves in hydrants occasionally fail to seal properly or even fail catastrophically as the result of deformation or other degradation of the main valve over time. Deformation and other degradation is typically caused by the mechanical forces that act on the valve during operation including when the valve is closed or being tightened. This deformation is typically caused by the flexibility of the material, such as rubber, used to make the valve or by the material of the outer portion of the valve that comes into contact with the hydrant in cases where the valve has an internal rigid structure formed from a different material. While incorporating an internal rigid structure in a valve can improve the performance and durability of the valve, problems associated with incorporating such structure include the difficulty in centering the structure and holding the structure in place during the manufacturing process, the difficulty in maintaining a consistent shell thickness around the structure, and corrosion of the rigid structure due to exposure to water necessitated by the design of the valve or the process for manufacturing the valve.

SUMMARY

Disclosed is a main valve for a hydrant including an internal rigid structure including a top surface, a bottom surface, and a locating feature, the locating feature defined in a one of the top surface and the bottom surface; and an outer shell at least partially enclosing the internal rigid structure and interacting with the locating feature.

Also disclosed is a hydrant including a hydrant body defining an inlet and an outlet, the inlet connectable to a fluid supply; and a main valve having an internal rigid structure and an outer shell at least partially enclosing the internal rigid structure, the main valve coupled to the hydrant body and mountable between the outlet of the hydrant body and the fluid supply, the outlet of the hydrant body sealable by the main valve, the internal rigid structure including a top surface, a bottom surface, a side surface, and a locating feature, the locating feature interacting with the outer shell.

Also disclosed is a method of manufacturing a main valve of a hydrant including forming an internal rigid structure including a top surface, a bottom surface, a side surface, and a locating feature, the locating feature defined in a one of the top surface and the bottom surface; positioning the internal rigid structure in a mold by contacting the locating feature with the mold; and forming an outer shell around the internal rigid structure.

DETAILED DESCRIPTION

Disclosed is a main valve and associated methods, systems, devices, and various apparatus. The main valve includes an internal rigid structure. Exemplary main valves are shown and disclosed in U.S. Pat. No. 6,886,586 to Fleury, et al. and in U.S. Patent Publication No. 2014/0261699 to Gifford, both of which are hereby incorporated by reference in their entireties. It would be understood by one of skill in the art that the disclosed main valve is described in but a few exemplary embodiments among many. No particular terminology or description should be considered limiting on the disclosure or the scope of any claims issuing therefrom.

One embodiment of a main valve136mounted in a hydrant100is shown inFIG. 1and described below. In the current embodiment, the hydrant100is a dry-barrel fire hydrant having a hydrant body110, a bonnet108connected to the top of hydrant body110, a lower barrel112connected to the bottom of hydrant body110, and a hydrant shoe132connected to the bottom of lower barrel112. In various embodiments, the hydrant shoe132of the hydrant100may be connected to a water supply pipe or any other fluid supply pipe. In various embodiments, hydrant100may be other types of fire hydrants, such as a wet-barrel fire hydrant, and the disclosure of a dry-barrel fire hydrant should not be considered limiting. In the current embodiment, an operating nut102is mounted on the bonnet108and has a threaded connection (not shown) with a stem114. Stem114includes upper stem portion214aand lower stem portion214bin the current embodiment connected by a pair of clevis pins216a,bhaving cotter pins218a,b, respectively. In various other embodiments, the upper stem portion214aand lower stem portion214bmay be connected by any fastener in various embodiments, including welding, screws, or bolts, and the stem114may be a single unit in various embodiments.

In the current embodiment, a valve assembly130is coupled to the lower stem portion214b. The valve assembly130includes a main valve136, an upper valve plate138, and a lower valve plate134. In various embodiments, the valve assembly130is coupled to the lower stem portion214bby a cap nut140and a stem pin150. The cap nut140is connected to the lower stem portion214bin the current embodiment by threading240. The stem pin150extends through the lower stem portion214band connects with upper valve plate138. The main valve136, the upper valve plate138, and the lower valve plate134are thereby held between the stem pin150and the cap nut140. In various other embodiments, the valve assembly130may be mounted to the stem114by other methods including fasteners, brackets, threading on the upper valve plate138or the lower valve plate134, welding, or gluing. In various other embodiments, the upper valve plate138or the lower valve plate134may be formed integrally with stem114. The present disclosure of a stem pin150and a cap nut140should not be considered limiting.

In the current embodiment, the hydrant body110includes a pumper nozzle170defining a pumper nozzle outlet172and a hose nozzle180defining a hose nozzle outlet182. The pumper nozzle outlet172is covered by a pumper nozzle cap174and the hose nozzle outlet182is covered by a hose nozzle cap184. Pumper nozzle cap174and hose nozzle cap184are removable for attachment of a pumper and a hose, respectively, to the hydrant100.

As seen inFIG. 2, a drain ring housing120is secured between lower barrel112and hydrant shoe132via a bolt126—and also nut127in various embodiments—and is sealed with respect to lower barrel112using a gasket128. The drain ring housing120may be secured by other methods in different embodiments, such as gluing, welding, brackets, or other fasteners. In various embodiments, drain ring housing120includes a first housing210and a second housing211. A seat ring122is threadedly engaged to an interior portion of drain ring housing120through a threaded connection124. Seat ring122has a beveled seating surface123defined in an interior portion thereof for sealing against main valve136. Main valve136(shown in more detail inFIGS. 3-4) includes a side surface146, a top surface144, and a bottom surface148. In various embodiments, “surface” is intended to encompass three-dimensional surfaces such as the surface of a golf ball or the side surface146of the main valve136and not just flat or planar surfaces. In various embodiments, the top surface144does not include surfaces which in the current are described as a side surface such as the side surface146. In various other embodiments, the top surface144or the bottom surface148include angled or beveled surfaces that extend from radially inward or outward portions of the axially outermost portions of the top surface144or the bottom surface148. Unless otherwise specified, a surface or other feature that is ‘angled’ is one that intersects with a neighboring feature at an angle between zero and 180 degrees.

In the current embodiment, the upper valve plate138contacts the top surface144and the lower valve plate134contacts the bottom surface148. The side surface146defines a first beveled portion137disposed between the bottom surface148and the top surface144. In various embodiments, the upper valve plate138defines a hollow cavity290. In various embodiments, upper valve plate138defines a plurality of hollow cavities290. In various embodiments, the upper valve plate138defines a lower surface289through which hollow cavity290extends. In various embodiments, a radially-outward portion292of lower surface289of upper valve plate138supports a radially-outward portion of top surface144of main valve136and a radially-inward portion291of lower surface289supports select radially-inward portions of main valve136. In various embodiments, less than the entire top surface144of main valve136is supported by upper valve plate138. In various embodiments, less than the entire bottom surface148of main valve136is supported by lower valve plate134. Due to the rigidity provided to main valve136by internal rigid structure250, supporting the entire top surface144or the entire bottom surface148of main valve136is not necessary in various embodiments because the main valve136is able to resist deformation, including where portions of main valve136are not in direct contact with upper valve plate138or lower valve plate134. Moreover, the presence of internal rigid structure250inside main valve136helps prevent main valve136from being pulled up into seat ring122and into lower barrel112.

In operation in the current embodiment, to allow water to flow from the water supply pipe to the hydrant body110, operating nut102is turned in one direction, lowering stem114and thereby causing lower valve plate134to urge main valve136away from seat ring122such that first beveled portion137disengages from beveled seating surface123. To discontinue water flowing from the water supply pipe to the hydrant body110, operating nut102is turned in the opposite direction, raising stem114and thereby causing lower valve plate134to urge main valve136towards seat ring122such that first beveled portion137engages beveled seating surface123. The hose nozzle outlet182and the pumper nozzle outlet172are thereby at least indirectly sealable by main valve136.

FIG. 2also shows that main valve136includes an internal rigid structure250enclosed within an outer shell260. In various embodiments, the outer shell260is formed from a flexible, water-impervious material such as rubber or plastic. Further, in various embodiments, the internal rigid structure250is formed from a rigid material such as cast iron, hard plastic, stainless steel, or other materials having similar mechanical properties. However, the disclosure of cast iron, hard plastic, and stainless steel should not be considered limiting on the current disclosure. The internal rigid structure250may be a solid piece or a hollow shell in various embodiments. In the current embodiment, the internal rigid structure250is a solid piece and has a top profile that is ring-shaped (as shown inFIG. 3). In various embodiments, the internal rigid structure250may include one or more ring portions. In various embodiments, the internal rigid structure250may have a top profile shaped like a square, pentagon, hexagon, octagon, or any other shape. In various embodiments, the main valve136defines a bore320(shown inFIGS. 3-4) through the center of the main valve136. In various embodiments, bore320includes a radiused portion330and a radiused portion340having a radius R42and a radius R43, respectively. In various other embodiments, the main valve136may not define a bore320through the center of the main valve136where the stem shown in the current embodiment as stem114does not pass through main valve136. Further, in various embodiments, the internal rigid structure250may not be fully enclosed by outer shell260but may be only partially enclosed.

In various embodiments, the first beveled portion137of main valve136allows a sufficient seal to develop between first beveled portion137and a beveled seating surface123of seat ring122at a smaller diameter, thus providing a higher leak point. Therefore, a greater amount of force per unit area is applied at the interface between seat ring122and main valve136. As a result, sealing may be accomplished with less total force and less deformation of main valve136. Moreover, plastic creep of outer shell260into the gap G between upper valve plate138and seat ring122may not occur because angle B (shown inFIG. 4) between first beveled portion137and second beveled portion142(shown inFIG. 4) reduces the diameter of main valve136immediately adjacent to gap G, advantageously extending the life of the main valve136. As is described below, the same benefit is provided with respect to the bottom portion if/when the main valve136is ‘flipped’ in service.

FIGS. 3 and 4show a top view and a partial sectional view, respectively, of the main valve136. In the current embodiment, side surface146, top surface144, and bottom surface148are defined on outer shell260. As seen inFIGS. 3 and 4, the side surface146of main valve136defines a first beveled portion137, a second beveled portion142, a third beveled portion160, a fourth beveled portion162, and a radially outermost edge310. In various embodiments, the radially outermost edge310is rounded with radius R41around the perimeter of main valve136. As shown inFIG. 4, the first beveled portion137extends from a radially outermost edge310of side surface146to a second beveled portion142substantially at an angle A and second beveled portion142extends from first beveled portion137to top surface144substantially at an angle B, wherein angle B is larger than angle A. First beveled portion137provides a seating portion while the second beveled portion142represents additional material missing that limits creep and deformation to extend the useful life of the main valve136and better seating and sealing over the useful life of the valve assembly130. In various embodiments, the second beveled portion142may be achieved by creating a radius between the first beveled portion137and the top surface144.

As shown inFIG. 4, the third beveled portion160extends from radially outermost edge310to fourth beveled portion162at an angle C and fourth beveled portion162extends from third beveled portion160to bottom surface148substantially at an angle D, wherein angle D is larger than angle C. In various embodiments, the fourth beveled portion162may be achieved by creating a radius between the third beveled portion160and the bottom surface148.

In the current embodiment, angle C is approximately equal to angle A and angle D is approximately equal to angle B, though angles A and C and/or angles B and D, respectively, may be different from each other in various embodiments. Thus, in the current embodiment the top portion of main valve136, defined from the radially outermost edge310to and inclusive of the top surface144and including the portion of side surface146therebetween, is substantially identical to the bottom portion of main valve136defined from the radially outermost edge310to and inclusive of the bottom surface148and including the portion of side surface146therebetween. As a result, in various embodiments the main valve is symmetrical about a horizontal plane perpendicular to an axis of the main valve. This allows main valve136to be reversible such that if the top portion or upper half of main valve136becomes damaged or fatigued, main valve136may be ‘flipped’ over such that the third beveled portion160of main valve136may be used to form a seal with beveled seating surface123. Thus, reversible main valve136with improved sealing affords the ability to affect a repair even when a replacement part is not available. The matching contours of the top portion and bottom portion of main valve136may therefore facilitate more resilient and better sealing.

Further, as shown inFIG. 4, in the current embodiment, internal rigid structure250defines an inner surface252, a top surface254, a bottom surface258, and a side surface256. In the current embodiment, side surface256defines a radially outermost edge410, a first angled portion264extending from radially outermost edge410to top surface254, and a second angled portion268extending from radially outermost edge410to bottom surface258. In the current embodiment, first angled portion264has a first angle that is approximately equal to a second angle of second angled portion268, though the first angle and the second angle may not be equal in various embodiments. In addition, radially outermost edge410of internal rigid structure250, in the current embodiment, is approximately coplanar with radially outermost edge310of main valve136, though radially outermost edge410may not be coplanar with radially outermost edge310in various embodiments.

FIG. 4also shows the internal rigid structure250including a locating feature270defined in an axially outermost portion of top surface144and a locating feature280defined in an axially outermost portion of bottom surface148. In various embodiments, locating features270,280are described as annular grooves. In various embodiments, locating features can be shaped as any one or more of a group of recessed or protruding features in internal rigid structure250including, but not limited to, grooves, holes including center-punched holes, channels, cavities, slots or elongated holes, divots, pins, bosses with or without internal recesses, and recessed features that extend from a radially outer wall of the feature to the axial center of internal rigid structure250. In various embodiments, locating features270,280of internal rigid structure250are at least partially in contact with outer shell260. In various embodiments, locating features270,280aid in positioning internal rigid structure250relative to outer shell260during the manufacturing process.FIG. 5discloses a perspective view of the internal rigid structure250. Locating feature270defined in the axially outermost portion of top surface254is shown with a first side wall276and a second side wall274, both extending from and angled with respect to the axially outermost portion of top surface254. In various embodiments, the first side wall276and the second side wall274are orthogonal to the axially outermost portion of top surface254. In various embodiments, the top surface254of internal rigid structure250defines locating feature270including a locating feature bottom surface272. In various embodiments, the bottom surface258defines locating feature280including a locating feature bottom surface282(both shown inFIG. 7). In various embodiments, the intersection between locating feature bottom surface272and second side wall274or first side wall276of locating feature270includes a radius. In various embodiments, the intersection between locating feature bottom surface282and one or more side walls (not shown) of locating feature280includes a radius.

In addition, in the current embodiment, internal rigid structure250provides support to outer shell260such that main valve136is capable of withstanding higher operating pressures than main valves lacking internal rigid structure250, such as solid rubber main valves. Further, internal rigid structure250prevents main valve136from plastic creep occurring into gap G between upper valve plate138and seat ring122because the rigidity provided by internal rigid structure250reduces the volume of flexible material in main valve136and therefore the volume of material that can deform (shown inFIG. 7, height H3is typical of the thickness of the flexible material from which outer260is formed) just as it reduces the degree of deformation that is physically possible into gap G. In the current embodiment, first angled portion264provides support to first beveled portion137and second beveled portion142, and second angled portion268provides support to third beveled portion160and fourth beveled portion162. However, first angled portion264and second angled portion268may not be present in various embodiments, and internal rigid structure250may be included in various main valves not including any of first beveled portion137, second beveled portion142, third beveled portion160, and fourth beveled portion162.

In various embodiments, an overall thickness (as measured from top surface254to bottom surface258) and an overall diameter (measured to radially outermost edge410) of the internal rigid structure250is a substantial percentage of an overall thickness (as measured from top surface144to bottom surface148) and an overall diameter (measured to radially outermost edge310), respectively, of the main valve136, causing the internal rigid structure250to occupy most of the volume of the main valve136and causing outer shell260to be relatively thin in proportion to the thickness of internal rigid structure250. In various embodiments, the outer shell260is less rigid and more deformable than internal rigid structure250; therefore, in various embodiments the thinness of outer shell260minimizes the overall deformation of the main valve136or a particular portion thereof. In various embodiments, the thinness of outer shell260minimizes material costs for the outer shell260and is another reason to center internal rigid structure250in main valve136. In various embodiments, an internal rigid structure250that is not centered in main valve136will result in greater variation in the thickness of outer shell260in different portions of the main valve136when outer shell260is relatively thin in proportion to the thickness of internal rigid structure250than when outer shell260is thicker. In various embodiments, the overall thickness and overall diameter of the internal rigid structure250is greater than 50%, 75%, 80%, 90%, or as much as 95% or more of the overall thickness and overall diameter, respectively, of the main valve136, to reduce the thickness of outer shell260.

FIG. 6shows the internal rigid structure250together with a lower mold half600a, lower mold half600aincluding a plurality of locating pins610, each with an axial end surface611. Lower mold half600ais sized not to match the dimensions of internal rigid structure250but rather to match the outer dimensions of main valve136, which is molded using a mold600(shown inFIG. 7) which includes lower mold half600ain various embodiments. In various embodiments, lower mold half600aincludes three locating pins610, each attached to lower mold half600aand positioned radially equidistant from the center of a cavity601ain lower mold half600aused to form the shape of at least one half of main valve136. In various embodiments, a center of each of the plurality of locating pins610lies within a circle having a radius (not shown) equal to that in which the axial center line of locating features270or locating feature280also lies. In various embodiments, this radius is half of the average of diameters D1and D2shown inFIGS. 3 and 4.

FIG. 7shows the internal rigid structure250sandwiched between the lower mold half600aand an upper mold half600b. Upper mold half600b, like lower mold half600a, is sized not to match the dimensions of internal rigid structure250but rather to match the outer dimensions of main valve136, which is molded using the mold600resembling, at least in part, lower mold half600aand upper mold half600bin combination in various embodiments. The disclosure of mold600, however, should not be considered limiting because the mold used to produce main valve136as disclosed may differ in appearance from that shown in the current embodiment and may include additional features not explicitly disclosed herein, including but not limited to any channels or ports for introducing molten raw material into the mold, heating or cooling features, ejector pins, features for locating each of the mold halves with respect to the injection molding machine, and the like.

In various embodiments, upper mold half600bincludes a plurality of locating pins620. In various embodiments, upper mold half600bincludes three locating pins612, each attached to upper mold half600band positioned radially equidistant from the center C of cavity601bin upper mold half600bused to form the shape of the other half of main valve136. In various embodiments, locating pins610each have an outer diameter X2, and the axial end surface611of each locating pin610is positioned a distance equal to a height H1away from an axially outermost portion of a surface651aof lower mold half600a. In various embodiments, locating pins620each have a first outer diameter X1, a second outer diameter X3, a first axial end surface621, and a second axial end surface622. In various embodiments, the first axial end surface621is positioned a distance equal to a height H2away from an axially outermost portion of a surface651bof upper mold half600b, and the second axial end surface622is positioned a distance equal to a height H3away from the axially outermost portion of surface651bof upper mold half600b. The distance between the first side wall276and the second side wall274of the locating features270,280is the distance X1, although in various embodiments the distance is slightly greater than distance X1in order to allow for variation in the diameter X2of locating pin610or to allow for variation in the diameter X1of locating pins620. In various embodiments, X3is larger than X2. In various embodiments, a center of each of the plurality of locating pins620lies within a circle having a radius equal to that in which the axial center line of locating features270,280also lies. In various embodiments, this radius is half of the average of diameters D1and D2shown inFIGS. 3 and 4.

Therefore, in various embodiments locating pins610and locating pins620fit into locating features270,280. In various embodiments, it may be advantageous to reference or gauge from the bottom of locating features270,280and therefore use locating pins610. In various embodiments, the axial end surface611of each of locating pins610comes into mating contact with locating feature bottom surface282of locating feature280of internal rigid structure250. In various embodiments, the circumferential edge of axial end surface611of each of locating pins610includes a radius to improve the ease of which locating pins610fit into locating features270,280or else to accommodate radii at the bottom of locating features270,280. In various embodiments, the diameter of each of the locating pins610is reduced to approximately match that portion of locating feature bottom surfaces272,282that is flat so that the axial end surface611of locating pin610remains in mating contact with locating feature bottom surface282. While locating pins610and locating pins620are sized differently, at least in part, both locating pins610and locating pins620or any combination thereof and also variations thereof are able to hold internal rigid structure250in the proper position but by referencing different surfaces of internal rigid structure250in various embodiments.

In various embodiments, the internal surfaces of locating features270,280may be more difficult to clean of foreign matter during the manufacturing process than the axially outermost portion of either top surface254or bottom surface258of internal rigid structure250and so it is preferable to reference or gauge from the axially outermost portion of either top surface254or bottom surface258of internal rigid structure250and therefore use locating pins620. More specifically, the second axial end surface622of each of locating pins620comes into mating contact with bottom surface258of internal rigid structure250in various embodiments. In various embodiments, the circumferential edge of the first axial end surface621or the second axial end surface622of each of the locating pins620will each include a radius to improve the ease of which locating pins620fit into locating features270,280. In various embodiments, this radius on the circumferential edge of the first axial end surface621or the second axial end surface622of each of the locating pins620accommodates a radius between the axially outermost portion of top surface254and locating feature270or between the axially outermost portion of bottom surface258and locating feature280. In various embodiments, the diameter at the end of each of the locating pins620is tapered to improve the ease of which locating pins620fit into locating features270,280. In various embodiments, the taper will result in the diameter of locating pin620being greater at the intersection with the second axial end surface622than the diameter of locating pin620at the intersection with the first axial end surface621. In various embodiments, the locating pins of mold600are conical or frustoconical with annular groove having a matching cross-section—i.e. having walls that include a draft angle or having side walls otherwise angled at an angle other than 90 degrees from the top surface254or bottom surface258. In various other embodiments, the locating pins are not conical or frustoconical in shape. In various embodiments, the locating pins are axially symmetric. In various embodiments, the side walls are symmetrical about an axial centerline of the annular groove to accommodate locating pins that are axially symmetric. In various embodiments, symmetry of the annular groove or the locating pins means that orienting the locating pins in mold600in any particular rotational position is unnecessary for purposes of matching the profile of the locating features. In various embodiments, bore320serves as a locating feature to accommodate one or more locating pins (not shown) to fix and maintain the position of internal rigid structure250during the encapsulation process.

Also disclosed is a method of manufacturing the main valve136of the hydrant100with the internal rigid structure250. In various embodiments, the method includes positioning the internal rigid structure250in mold600—including lower mold half600aand upper mold half600bin various embodiments. In various embodiments, the method includes the step of engaging the locating feature270or280with one or more locating pins610or620. In various embodiments, this method includes contacting the locating feature270,280of internal rigid structure250with the mold600. In various embodiments, the method includes positioning the internal rigid structure250so as to maintain the position of the internal rigid structure250in three spatial dimensions relative to a cavity601of mold600. In various embodiments, the method includes centering the internal rigid structure250inside the cavity601of mold600. In various embodiments, the method includes forming an outer shell260at least partially around the internal rigid structure250. In various embodiments, the method includes forming the outer shell260around the internal rigid structure250so as to fully enclose the internal rigid structure250within the outer shell260. In various embodiments, the method includes forming the outer shell260around the internal rigid structure250so as to fill the space between cavity601—which defines surface651aof cavity601aand surface651bof cavity601b—and the surface251of internal rigid structure250. In various embodiments, the outer shell260is formed with a flexible material defining a Shore-A durometer which is less than about 100, although the disclosure of a Shore-A durometer of less than about 100 should not be considered limiting on the present disclosure. In various embodiments, the Shore-A durometer of the material used in the outer shell260is about 95. In various embodiments, the outer shell260is formed from styrene-butadiene rubber. However, the disclosure of styrene-butadiene rubber should not be considered limiting on the present disclosure. In various embodiments, the method will include filling voids created in the outer shell260of main valve136by locating pins610,620. In various embodiments, those voids will be filled with any one of a variety of materials including, but not limited to, epoxy, silicone, or rubber.

One should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” 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 steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular embodiments or that one or more particular embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. Moreover, unless specifically stated any use of the terms first, second, top, bottom, upper, lower, etc. do not denote any order or importance or absolute positioning, but rather the terms first, second, top, bottom etc. are used to distinguish one element from another. Further, the size, shape, thickness, and other dimensions and features of the various components shown in the figures are for illustrative purposes and should not be considered limiting. The drawings are not drawn to scale.