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Title:
PASSIVE LATCH MECHANISM FOR A DRILLING RIG MAST
Document Type and Number:
WIPO Patent Application WO/2017/066788
Kind Code:
A1
Abstract:
An automatic mast section latching system is disclosed that provides rapid and safe connection of sequential mast sections without placing an employee in a lift to complete the task. A slot flange extends above each mast section for connecting to a pin section extending below a mast section above it. A first pin and a second pin extend perpendicularly from each pin flange. A slot is formed on the slot flange for receiving the first pin. A ramp is formed on the top of the slot flange. A seat is formed on the ramp for receiving the second pin.

Inventors:
TREVITHICK MARK W (US)
Application Number:
PCT/US2016/057394
Publication Date:
April 20, 2017
Filing Date:
October 17, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SCHLUMBERGER TECHNOLOGY CORP (US)
SCHLUMBERGER CA LTD (CA)
SERVICES PETROLIERS SCHLUMBERGER (FR)
SCHLUMBERGER TECHNOLOGY BV (NL)
International Classes:
E21B15/00; E04H12/34; E21B7/02
Domestic Patent References:
WO2005075789A12005-08-18
Foreign References:
US20150059262A12015-03-05
US20120107080A12012-05-03
US20050194189A12005-09-08
US20130305632A12013-11-21
Attorney, Agent or Firm:
GREENE, Rachel et al. (23500 Colonial ParkwayKaty, TX, US)
Download PDF:
Claims:
CLAIMS:

1. A drilling rig mast, comprising:

a first mast section;

a second mast section;

a slot flange extending beyond an end of the first mast section;

a pin flange extending beyond an end of the second mast section;

a first pin extending outward from the pin flange;

a second pin extending outward from the pin flange;

a slot formed on the slot flange, the slot configured to receive the first pin;

a ramp formed on an end of the slot flange; and

a radial seat formed on the ramp, the seat configured to receive the second pin when the first pin is located in the slot,

the first mast section connectable to the second mast section by location of the first pin in the slot and location of the second pin in the seat.

2. The drilling mast of Claim 1, further comprising:

the seat forming a radial relief on the ramp.

3. The drilling mast of Claim 2, further comprising:

the seat being non-tangential to the ramp to form a ramp inflection between them.

4. The drilling mast of Claim 2, further comprising:

a compression arc formed on the seat, beginning at the ramp inflection.

5. The drilling mast of Claim 4, further comprising:

the compression arc being at least 45 degrees.

6. The drilling mast of Claim 1, further comprising:

the slot having a slide and an edge, and a radial cup connecting the slide to the edge; and

the distance from a center of the cup to a center of the seat being equal to the distance between the center of the first pin and the center of the second pin.

7. The drilling mast of Claim 6, further comprising:

the radial cup being non-tangential to the edge of the slot to form a slide inflection between them.

8. The drilling mast of Claim 7, further comprising:

a tension arc formed on the cup, beginning at the slide inflection.

9. The drilling mast of Claim 8, further comprising:

the tension arc being at least 45 degrees.

10. The drilling mast of Claim 6, further comprising:

the cup being non-tangential to the edge.

11. The drilling mast of Claim 2, further comprising:

the ramp being inclined in the direction of the slot, at an angle of between 10 and 20 degrees.

12. The drilling mast of Claim 3, further comprising:

the slide being inclined in an amount slightly greater than that of the ramp.

13. The drilling mast of Claim 1, further comprising:

the second pin being laterally offset from the first pin by at least the amount by which the cup center is offset from the seat center.

14. A drilling rig mast, comprising:

a first mast section having a front side and opposing rear side, and a top end and an opposing bottom end;

a second mast section having a front side and opposing rear side, and a top end and opposing bottom end;

a slot flange extending upward from the top end of the rear side of the first mast section;

a pin flange extending downward from the bottom end of the rear side of the second mast section;

a pin extending outward from the pin flange; and a slot formed on the slot flange, the slot configured to receive the first pin, location of the pin in the slot aligns an opposing pair of pinned connections between the first and second mast sections on their front side.

15. A method of connecting consecutive sections of a drilling mast, comprising:

pivotally connecting a lower end of a first mast section to a drilling floor, the first mast section having a slot flange on an upper end;

providing a slot having a cup and a ramp having a seat on the slot flange;

inclining the first mast section into a position below a horizontal plane;

providing a second mast section having a pin flange on its lower end;

providing a first pin and a second pin on the pin flange;

moving the lower end of the second mast section towards the upper end of the first mast section until the second pin engages the ramp;

raising the inclination of the first mast section until the first pin moves into the slot cup;

raising the inclination of the first mast section until the second pin moves into the seat; and

connecting a front side of the first and second mast sections together.

16. A method of connecting consecutive sections of a drilling mast, comprising:

pivotally connecting a lower end of a first mast section to a drilling floor;

inclining the first mast section into a position below a horizontal plane;

moving a lower end of a second mast section towards the upper end of the first mast section;

engaging a second pin on a pin flange on the lower end of the second mast section with a ramp on a slot flange on the upper end of the first mast section; raising the inclination of the first mast section until a first pin on the pin flange is positioned in a cup on the slot flange;

raising the inclination of the first mast section until the second pin is positioned in a seat on the slot flange; and

connecting a front side of the first and second mast sections together.

Description:
PASSIVE LATCH MECHANISM FOR A DRILLING RIG MAST BACKGROUND

[001] In the exploration of oil, gas and geothermal energy, drilling operations are used to create boreholes, or wells, in the earth. Drilling rigs used in subterranean exploration are transported to the locations where drilling activity is to be commenced. These locations are often remotely located in rough terrain. The transportation of such rigs on state highways is performed in compliance with highway safety laws and clearance underneath bridges or inside tunnels. Once transported to the desired location, large rig components are moved from a transport trailer into engagement with the other components located on the drilling pad.

[002] Moving a full-size drilling rig includes disassembly and reassembly of the substructure and mast. Safety is of paramount importance. Speed of disassembly and reassembly impact profitability. Complete disassembly leads to errors and delay in reassembly. Modern drilling rigs may have two, three, or even four mast sections for sequential connection and raising above a substructure.

[003] The lower mast section is delivered and positioned by truck into proximity and alignment with the substructure. The front pair of lower mast section legs is aligned and pin connected to front shoes on the drill floor. The lower mast section truck then departs. The lower mast section is connected to the mast raising cylinders to enable height adjustment of the lower mast section. This is done, in part, because variations in the terrain surrounding the drilling rig render alignment difficult. The center mast section is then delivered and positioned by truck into proximity and alignment with the upper end of the lower mast section. At this stage, the four corners of the lower mast and center mast sections are aligned to permit connection.

[004] Connection of the front side of the lower mast section to the center mast section can be accomplished from ground level. However, connection of the rear side of the lower mast section to the center mast section involves placing rig personnel in a lift and raising them over the suspended and unconnected mast sections. From a position above the unconnected lower and center mast sections, the rig personnel can help direct their alignment to the truck driver and operator of the mast raising cylinders to permit placement of pins into the rear leg connectors. [005] There are well-recognized inherent risks associated with raising personnel above ground and above unconnected structures. Additional risks are realized when one of the unconnected structure components is located on a vehicle. Additional risks are realized when the terrain is uneven and unpaved. It is desirable to reduce these risks.

[006] After connection of the center mast section to the lower mast section, the center mast section truck departs, and the upper mast section truck arrives. At this stage, the four corners of the center mast section and upper mast section are aligned to permit connection. With the mast section now extended further off of the substructure, mast section alignment may be more difficult. Rig personnel is again positioned in a lift suspended above the two unconnected mast sections to complete connection of the rear side of the center mast section to the upper mast section.

[007] When the upper mast section is securely connected to the center mast section, the upper mast truck departs. If the mast is a three section mast, it is now fully assembled and the assembled mast is raised vertically above the drill floor. If the mast is a four section mast, the crown mast section will now arrive on a crown section truck.

[008] At this stage, the four corners of the upper mast section and crown mast section are aligned to permit connection. With the partially assembled mast section now extended further off of the substructure, alignment will be even more difficult for the reasons stated above. Once again, rig personnel is positioned into a lift suspended above the two unconnected mast sections to complete connection of the rear side of the upper mast section to the crown mast section. When connected, the crown section truck departs.

[009] The fully assembled mast is then raised by pivoting it on the pin connection to the drill floor with lifting force supplied by the mast raising cylinders. When fully erect, the rear mast legs of the lower mast section are pin connected to the rear shoes on the drill floor.

[010] It is desirable to have a connection system that reduces rig-up and rig-down time. It is desirable to have a system that provides improved alignment and connectivity between sequential mast sections during rig-up. It is highly desirable to have a system with a lower risk of accidents.

[011] In particular, it is desirable to provide a mast latching system that enables connection of sequential mast sections without the need to expose personnel to the safety hazards associated with working from a lift device above large, unconnected sections of a drilling rig mast.

[012] The disclosed embodiments provide a novel solution to the engineering constraints and challenges of providing a rapid, safe, and reliable connection between mast sections of a drilling rig.

SUMMARY

[013] A drilling rig mast system is provided, having a first mast section and a series connectable second mast section. A slot flange extends beyond an end of the first mast section. A pin flange extends beyond an end of the second mast section for engagement with the slot flange. A first pin extends outward from the pin flange. A second pin also extends outward from the pin flange.

[014] A slot is formed on the slot flange and is configured to receive the first pin. A ramp is formed on the end of the slot flange and is configured to engage the second pin. A seat is formed on the ramp of the slot flange. The seat is configured to receive the second pin when the first pin is located in the slot.

[015] The first mast section is connectable to the second mast section by location of the first pin in the slot and location of the second pin in the pin seat. When the pins are located in the slot and seat, respectively, the first and second mast sections are sufficiently connected at the rear side of the mast such that pins may then be connected by rig personnel on the ground. This method can then be repeated for each successive section of mast added.

[016] As will be understood by one of ordinary skill in the art, the assembly disclosed may be modified and the same advantageous result obtained. In particular, one of ordinary skill in the art will recognize that the pin flange and slot flange may be reversed in orientation as between sequential sections of the mast or other large truss system.

BRIEF DESCRIPTION OF THE DRAWINGS

[017] FIG. 1 is a side view of a drilling rig with the lower mast section pinned to the drill floor and the center mast section being attached to the lower mast section and illustrating one embodiment of the passive mast latch mechanism. [018] FIG. 2 is a side view of an embodiment of the slot flange of the passive mast latch mechanism.

[019] FIG. 3 is a side view of an embodiment of the pin flange of the passive mast latch mechanism.

[020] FIG. 4 is a side view of the pin flange of FIG. 3 engaged with the slot flange of FIG. 2, and illustrating certain properties of the engagement of this embodiment.

[021] FIG. 5 is a side view of a step of the connection method of an embodiment, illustrating a first mast section having a slot flange on its upper end. The first mast section is in the proper angular position for approach by a second mast section having a pin flange on its lower end.

[022] FIG. 6 is a side view of another step of the connection method of an embodiment, illustrating the ramp of the slot flange impacted by the second pin of the pin flange, and illustrating the first pin positioned above the slot of the slot flange.

[023] FIG. 7 is a side view of another step of the connection method of an embodiment, illustrating the first mast section raised sufficiently to permit the first pin to engage in the slot.

[024] FIG. 8 is a side view of another step of the connection method of an embodiment, illustrating the first mast section raised sufficiently further to engage the second pin in the seat below the ramp, and to align the front side of the first and second mast sections to permit them to be manually pinned together.

[025] FIG. 9 is a side view of an optional step of the connection method of an embodiment, illustrating the second mast section having a slot flange on its upper end. The second mast section is in the proper angular position for approach by a third mast section having a pin flange on its lower end.

[026] FIG. 10 is a side view illustrating an optional step of the connection method, which is substantially a repeat of the second method step, illustrated as performed as between the second and third mast sections.

[027] FIG. 11 is a side view of an optional step of the connection method of an embodiment, which is substantially a repeat of the third method step, illustrated as performed as between the second and third mast sections. [028] FIG. 12 is a side view of an optional step of the connection method of an embodiment, which is substantially a repeat of the fourth method step, illustrated as performed as between the second and third mast sections.

[029] FIG. 13 is a side view illustrating the first mast section positioned for connection to the second mast section with the passive latch system.

[030] FIG. 14 is a side view illustrating the first and second mast sections positioned for approach by the third mast section.

[031] FIG. 15 is a side view illustrating the first and second mast sections positioned for connection to the third mast section with the passive latch system.

[032] FIG. 16 is a side view illustrating the first, second, and third mast sections positioned for approach by the fourth mast section.

[033] FIG. 17 is a side view illustrating each of the first, second, third, and fourth mast sections connected in series with an embodiment of the passive latch system of the present invention.

[034] The steps listed above are not inclusive or exclusive of the numerous other procedures related to the rig-up or rig-down of a drilling rig. The features and benefits of the disclosed embodiments will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements.

[035] The drawings constitute a part of this specification and include embodiments that may be embodied in various forms. It is to be understood that in some instances various aspects of the embodiments described may be shown exaggerated or enlarged to facilitate an understanding of the embodiments.

DETAILED DESCRIPTION

[036] The following description is presented to enable any person skilled in the art to make and use the disclosed embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. In particular, it will be recognized the relative positions of the slot flanges and pin flanges can be reversed to provide the equivalent structure, function, method, and result of the embodiments disclosed.

[037] FIG. 1 is a side view of one embodiment of a drilling rig 1. Drilling rig 1 has an expandable substructure 10. Substructure 10 has a drill floor 12 generally spanning across its top. A pair of front shoes 14 extends above drill floor 12. A pair of rear shoes 16 extends above drill floor 12. A pair of mast raising cylinders 20 is connected to substructure 10.

[038] A first ("lower") mast section 100 is provided. First mast section 100 may be generally rectilinear, having a front side 102 and an opposite rear side 104, as well as a conventionally known Driller's side (shown) and an opposite Off-Driller's side (not visible, but opposite to the Driller's side). First mast section 100 has a pair of front legs 106 and a pair of rear legs 108 at its lower end. First mast section 100 has an opposite upper end 110.

[039] Front legs 106 of a first mast section 100 are pivotally pin connected to front shoes 14. Rear legs 108 are pin connectable to rear shoes 16 upon pivoted erection of first mast section 100 into a vertical orientation above drill floor 12.

[040] First mast section 100 is raised into the vertical position above drill floor 12 by a pair of raising cylinders 20. Raising cylinders 20 are capable of controlling the angular disposition of first mast section 100, however, as a person of ordinary skill in the art of drilling rig design will appreciate, drilling masts are conventionally raised by one or more pairs of hydraulic cylinders arranged in various configurations depending upon the rig size, weight, and design configuration. For example, a pair of boost cylinders is commonly incorporated. Therefore, as used herein, "mast raising cylinders" 20 is intended to include any such combination or configuration of expandable cylinders used to control the angularity of the individual, partially assembled, and assembled mast sections relative to the drill floor during assembly and erection of the mast.

[041] Referring again to FIG. 1, a pair of conventional pin connections 120 is provided on front side 102 of first mast section 100, proximate to upper end 110. A pair of slot flanges 500 is provided on each side (Driller's side and Off-Driller's side) of upper end 110 of rear side 104 of first mast section 100.

[042] A second ("center") mast section 200 is provided for series connection to upper end 110 of first mast section 100. Second mast section 200 may be generally rectilinear. It has a front side 202 and an opposite rear side 204. Front side 202 and rear side 204 are separated by a conventionally known Driller's side (shown facing the page) and an opposite Off-Driller's side (not visible, opposite to the Driller's side). Second mast section 200 has a lower end 208 and an opposite upper end 210. A pair of pin flanges 600 is provided on each side (Driller's side and Off-Driller's side) of lower end 208 of rear side 204 of second mast section 200. A pair of conventional pin connections 220 is provided on front side 202 of lower end 208 of second mast section 200 for connection to pin connections 120 on front side 102 of upper end 110 of first mast section 100. A pair of conventional pin connections 230 may be provided on front side 202 of upper end 210 of second mast section 200 for connection to another mast section.

[043] FIG. 2 is a side view of an embodiment of slot flange 500 of the passive mast latch mechanism. As seen in this view, slot flange 500 has a slot 510, comprising a slide 512, a cup 514, and an edge 516. Cup 514 connects slide 512 to edge 516. In the embodiment illustrated in FIG. 2, cup 514 is non-tangent to edge 516 at slide inflection 518. From a center 520, cup 514 has a radius 522 that extends over an included arc 524. A tension arc 526 is within included arc 524, terminating at slide inflection 518.

[044] Also formed on slot flange 500 is an impact ramp 532. A seat 534 is formed at the bottom of impact ramp 532. From a center 540, seat 534 has a radius 542 that extends over an included arc 544, terminating at ramp inflection 538. In the embodiment illustrated in FIG. 2, seat 534 is non-tangent to impact ramp 532 at ramp inflection 538.

[045] Also in the embodiment illustrated, impact ramp 532 is non-parallel to slide 512. In particular, angle 528 of slide 512 is slightly greater than angle 548 of impact ramp 532. Also in the embodiment illustrated, center 520 of cup 514 and center 540 of seat 534 are separated by a distance 550, with center 520 of cup 514 disposed closer to rear surface 104 of first mast section 100 than is center 540 of seat 534.

[046] FIG. 3 is a side view of one embodiment of a pin flange 600 of the passive mast latch mechanism. In the embodiment illustrated, pin flange 600 is attached to each side (Driller's side and Off-Driller's side) of lower end 208 of rear side 204 of a second mast section 200. These two pin flanges 600 are thus positioned for engagement with two opposing slot flanges 500 located on the upper end 110 of rear side 104 of first mast section 100 (See Fig. 1). [047] Each pin flange 600 has a first pin 610 and a second pin 620. Pin 610 has a diameter that renders it receivable in cup 514 of slot 510. Pin 620 has a diameter that renders it receivable in seat 534 at the end of impact ramp 532.

[048] FIG. 4 is a side view of pin flange 600 of FIG. 3 engaged with slot flange 500 of FIG. 2, and illustrating certain properties of the engagement of this embodiment. As represented in FIG. 4, a tensile force T is present and acting on first pin 610 when assembled mast sections 100 and 200 are rotated about front shoe 14 connections by lifting cylinders 20 into a vertical position above drill floor 12. When erect, wind loads create tensile force T at first pin 610. To tolerate tensile force T without the urge to disengage, a tension bearing zone is provided along tension arc 526. Tension arc 526 extends to within included arc 524, and terminates at slide inflection 518. For safety, the included angle of tension arc 526 should be at least about 35-45 degrees.

[049] In addition to providing a tension bearing zone, the location of slide inflection 518 provides resistance to disengagement of first pin 610 from slot 510 when first pin 610 experiences tensile load T.

[050] The remainder of included arc 524 resists shear forces S resulting from the extension of raising cylinders 20 when using the passive latch mechanism, such as will be described in the third and fourth method steps below.

[051] Still referring to FIG. 4, a compressive force C is present and acting on second pin 620 when the assembled mast sections 100 and 200 are rotated about front shoe 14 connections by lifting cylinders 20 into a vertical position above drill floor 12. When erect, the weight of the fully assembled mast and drill string create compressive force C at second pin 620. To tolerate compressive force C without the urge to disengage, a compressive bearing zone is provided along compression arc 546. Compression arc 546 is within included arc 544, and terminates at ramp inflection 538. For safety, the minimum including angle of compression arc 546 is about 35 to 45 degrees.

[052] In addition to providing a compressive bearing zone, the location of ramp inflection 538 provides resistance to disengagement of second pin 620 from cup 534 when second pin 620 experiences compressive force C.

[053] The remainder of included arc 544 resists shear forces S resulting from the extension of raising cylinders 20 when using the passive latch mechanism, such as will be described in the third and fourth method steps below. [054] FIG. 5 is a side view of the first step of the connection method of an embodiment, illustrating first mast section 100 angularly positioned by manipulation of raising cylinders 20 to permit approach by a second mast section truck (not shown) supporting second mast section 200 having pin flange 600 on its lower end 208.

[055] FIG. 6 is a side view of the second step of the connection method of an embodiment, illustrating second mast section 200 moved into contact with first mast section 100. In this view, second pin 620 has come in contact with impact ramp 532, positioning first pin 610 above slot 510, and preventing further movement of second mast section 200 in the direction of first mast section 100.

[056] FIG. 7 is a side view of the third step of the connection method of an embodiment, illustrating first mast section 100 raised slightly by raising cylinders 20 in relation to second mast section 200 sufficiently such that first pin 610 moves into slot 510, such as by sliding along slide 512 or edge 516 or other means, until first pin 610 has come to rest in cup 514.

[057] FIG. 8 is a side view of the fourth step of the connection method of an embodiment, illustrating first mast section 100 raised slightly further by raising cylinders 20 in relation to second mast section 200 sufficiently such that second pin 620 is moved into a position of complementary fit in seat 534. In moving into the illustrated position, second pin 620 departs from impact ramp 532 as it passes ramp inflection 538. In this position, engagement of first pin 610 in cup 514 and engagement of second pin 620 in seat 534 aligns pin connection 120 of first mast section 100 with pin connection 220 of second mast section 200 such that they may be pin connected by rig personnel. Pinning a connection between front side 102 of first mast section 100 and front side 202 of second mast section 200 may be performed from the ground, without placing personnel in an elevated lift basket.

[058] FIG. 9 is a side view of an optional fifth step of the connection method of an embodiment. Connected first and second mast sections 100 and 200 are raised slightly further by raising cylinders 20 to permit the second mast section truck to be removed from its position of support of second mast section 200. Connected first and second mast sections 100 and 200 are then angularly positioned by manipulation of raising cylinders 20 to permit approach by a third mast section truck (not shown) supporting a third ("upper") mast section 300 having pin connection 330 on its lower end 308. [059] FIG. 10 is a side view illustrating an optional sixth step of the connection method, which is substantially a repeat of the second method step. In this sixth step, third mast section 300 is moved into contact with second mast section 200. In this view, second pin 620 has come in contact with impact ramp 532, positioning first pin 610 above slot 510, and preventing further movement of third mast section 300 in the direction of second mast section 200.

[060] FIG. 11 is a side view of an optional seventh step of the connection method of an embodiment, which is substantially a repeat of the third method step. In this seventh step, connected first and second mast sections 100 and 200 are raised slightly by raising cylinders 20 in relation to third mast section 300 sufficiently such that first pin 610 moves into slot 510, such as by sliding along slide 512 or edge 516 or other means, until first pin 610 has come to rest in cup 514.

[061] FIG. 12 is a side view of an optional eighth step of the connection method, which is substantially a repeat of the fourth method step. In this eighth step, connected first and second mast sections 100 and 200 are raised slightly further by raising cylinders 20 in relation to third mast section 300 sufficiently such that second pin 620 is moved into a position of complementary fit in seat 534. In moving into the illustrated position, second pin 620 departs from impact ramp 532 as it passes ramp inflection 538 (See Fig. 2). In this position, engagement of first pin 610 in cup 514 and engagement of second pin 620 in seat 534 aligns pin connection 230 of second mast section 200 with pin connection 330 of third mast section 300 such that they may be pin connected by rig personnel. Pinning a connection between front side 202 of second mast section 200 and front side 302 of third mast section 300 may be performed from the ground, without placing personnel in an elevated lift basket.

[062] FIG. 13 is a side view illustrating first mast section 100 positioned for connection to second mast section 200 with an embodiment of the passive latch system.

[063] FIG. 14 is a side view illustrating first and second mast sections (100, 200) positioned for approach by third mast section 300.

[064] FIG. 15 is a side view illustrating first and second mast sections (100, 200) positioned for connection to third mast section (300) with an embodiment of the passive latch system. [065] FIG. 16 is a side view illustrating first, second, and third mast sections (100, 200, 300) positioned for approach by a fourth ("crown") mast section 400.

[066] FIG. 17 is a side view illustrating each of first, second, third, and fourth mast sections (100, 200, 300, 400) connected in series with an embodiment of the passive latch system between each successive mast section.

[067] It has thus been illustrated that the presently disclosed passive latch mechanism provides a mast connection system that is automated to reduce rig-up and rig-down time. It provides for fast and automatic alignment and connection of sequential mast sections without positioning personnel in a lift above disconnected mast sections for the purposes of directing alignment and installing or removing pins.

[068] If used herein, the term "substantially" is intended for construction as meaning "more so than not."

[069] It is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing detailed description. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosed embodiments.