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Title:
WHEELCHAIR LEGREST ASSEMBLY
Document Type and Number:
WIPO Patent Application WO/2012/044941
Kind Code:
A1
Abstract:
A powered wheelchair (40) includes a seat assembly (46) configured to support an individual, a curved legrest assembly (48) pivotally connected to the seat assembly, and an adjustment assembly including an actuator (68) operatively connected to the central column (50) through a piston (64) slidably secured within a sleeve (66). The adjustment assembly is secured underneath the seat assembly. The powered wheelchair may also include an extension bracket ( 58) that allows legrests (56) and a central column (50) of the curved legrest assembly (48) to be separately and independently adjusted with respect to one another.

Inventors:
ENGMAN BO (SE)
LIND URBAN (SE)
BACKSTROM NIKLAS (SE)
JAHKEL JONAS (SE)
MIRZAIE MEHDI (US)
Application Number:
PCT/US2011/054242
Publication Date:
April 05, 2012
Filing Date:
September 30, 2011
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
PERMOBIL AB (SE)
ENGMAN BO (SE)
LIND URBAN (SE)
BACKSTROM NIKLAS (SE)
JAHKEL JONAS (SE)
MIRZAIE MEHDI (US)
International Classes:
A61G5/12
Foreign References:
EP1522297A22005-04-13
US6276704B12001-08-21
EP1997466A22008-12-03
US20060071531A12006-04-06
US6375209B12002-04-23
Other References:
None
Attorney, Agent or Firm:
ARNOLD, Patrick J. et al. (Held & Malloy Ltd.500 West Madison Street,Suite 340, Chicago Illinois, US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A wheelchair comprising:

a seat assembly configured to support an individual;

a curved legrest assembly pivotally connected to said seat assembly; and

an adjustment assembly secured underneath said seat assembly, wherein said adjustment assembly is configured to adjust said curved legrest assembly through a range of motion.

2. The wheelchair of claim 1, wherein said legrest assembly includes a curved central column secured to curved legrest beams.

3. The wheelchair of claim 2, wherein said curved central column comprises a first beam slidably secured to a second beam.

4. The wheelchair of claim 2, wherein said curved central column is adjustably secured to said curved legrest beams through an extension bracket that allows for each of said curved central column and said curved legrest beams to be independently adjusted with respect to one another.

5. The wheelchair of claim 4, wherein said extension bracket comprises a central channel and two lateral channels, wherein said curved legrest beams are adjustably secured within said lateral channels, and wherein said central column is adjustably secured within said central channel.

6. The wheelchair of claim 5, wherein each of said central channel and said lateral channels connects to at least one threaded bore configured to receive a set screw.

7. The wheelchair of claim 1, further comprising a bracing bracket having a curved track secured underneath said seat assembly, and wherein said central column connects to said bracing bracket through a rolling bracket having rollers abutting said curved track.

8. The wheelchair of claim 7, wherein said rolling bracket is spring-biased with respect to said central column.

9. The wheelchair of claim 1, wherein said adjustment assembly includes an actuator operatively connected to said curved legrest assembly through a piston slidably secured within a sleeve.

10. A legrest assembly for a wheelchair comprising:

a curved central column having an end configured to be pivotally connected to a seat assembly of the wheelchair;

a first curved legrest beam secured to one side of said curved central column; and a second curved legrest beam secured to an opposite side of said curved central column.

11. The legrest assembly of claim 10, wherein said curved central column comprises a male beam slidably secured to a female beam, and wherein said first and second curved legrest beams are secured to said female beam.

12. The legrest assembly of claim 10, further comprising an extension bracket adjustably secured to each of said curved central column and said first and second curved legrest beams, wherein said extension bracket secures said first and second curved legrest beams to said curved central column, and wherein said extension bracket allows for each of said curved central column and said first and second curved legrest beams to be independently adjusted with respect to one another.

13. The legrest assembly of claim 12, wherein said extension bracket comprises a central channel and first and second lateral channels, wherein said first and second curved legrest beams are adjustably secured within said first and second lateral channels, respectively, and wherein said central column is adjustably secured within said central channel.

14. The legrest assembly of claim 13, wherein each of said central channel and said first and second lateral channels connects to at least one threaded bore configured to receive a set screw.

15. A powered wheelchair comprising:

a support base having wheels;

a seat assembly supported by said support base;

a curved legrest assembly pivotally connected to said seat assembly, wherein said curved legrest assembly includes (i) a curved central column having an end configured to be pivotally connected to a seat assembly of the wheelchair, (ii) a first curved legrest beam secured to one side of said curved central column, (iii) a second curved legrest beam secured to an opposite side of said curved central column, and (iv) an extension bracket adjustably secured to each of said curved central column and said first and second curved legrest beams, wherein said extension bracket secures said first and second curved legrest beams to said curved central column, and wherein said extension bracket allows for each of said curved central column and said first and second curved legrest beams to be independently adjusted with respect to one another; and

an adjustment assembly including an actuator operatively connected to said central column through a piston slidably secured within a sleeve, wherein said adjustment assembly is secured underneath said seat assembly.

16. The powered wheelchair of claim 15, wherein said curved central column comprises a male beam slidably secured to a female beam, and wherein said first and second curved legrest beams are secured to said female beam.

17. The powered wheelchair of claim 15, wherein said curved legrest outwardly bows out from ends to a central area.

18. The powered wheelchair of claim 15, wherein said extension bracket comprises a central channel and first and second lateral channels, wherein said first and second curved legrest beams are adjustably secured within said first and second lateral channels, respectively, and wherein said central column is adjustably secured within said central channel.

19. The powered wheelchair of claim 18, wherein each of said central channel and said first and second lateral channels connects to at least one threaded bore configured to receive a set screw.

20. The powered wheelchair of claim 15, further comprising a bracing bracket having a curved track secured underneath said seat assembly, and wherein said central column connects to said bracing bracket through a rolling bracket having rollers abutting said curved track, wherein said rollers are operatively connected to a web belt that also operatively connects to a clamp positioned on said central column.

21. The powered wheelchair of claim 20, wherein said rolling bracket is spring- biased with respect to said central column.

Description:
TITLE

WHEELCHAIR LEGREST ASSEMBLY

FIELD OF EMBODIMENTS OF THE INVENTION

[0001] Embodiments of the present invention generally relate to wheelchairs, and, more particularly, to legrest assemblies for wheelchairs.

BACKGROUND

[0002] Power wheelchairs are used by disabled individuals in order to move around in comfort and relative ease. Indeed, these wheelchairs have improved throughout the years to provide numerous features that provide additional comfort to individuals.

[0003] A power wheelchair typically includes a base having wheels. The base supports a seat assembly. The individual controls operation of the wheelchair through a control interface, such as a joystick, typically positioned on an armrest of the seat assembly. The control interface is in electrical communication with a processing system that is also connected to motors that drive the wheels, a steering mechanism, and the like. The processing system generally controls overall operation of all powered aspects of the wheelchair.

[0004] A wheelchair also includes legrests in which an individual positions his/her legs. Many legrests are adjustable such that they may be moved through various positions.

[0005] Figures 1 and 2 illustrate isometric side and front views, respectively, of a conventional power wheelchair 10. As shown in Figures 1 and 2, the wheelchair 10 includes a seat assembly 12 and a legrest assembly 14 connected to the seat assembly 12. The legrest assembly 14 includes a central column 16 extending from and proximate to a front edge of the seat assembly 12. Calf supports 18 are positioned on either side of the central column 16 below the seat assembly 12. Footrests 20 extend from an end of the column 16 that is distal from the seat assembly 12. As shown, in the normal position, the footrests 20 are generally parallel with the seating area of the seat assembly 12, while the calf supports 18 and central column 16 are generally perpendicular to the seating area.

[0006] The legrest assembly 14 may be adjusted so that it may rotate upward about an area where it connects to the seat assembly 12. That is, a proximal end of the central column 16 is pivotally connected to the seat assembly 12. [0007] In order to adjust the legrest assembly 14, an actuator 22 may be engaged to move the legrest assembly 14. As shown in Figure 1, the actuator 22 is positioned behind the legrest assembly 14. The actuator 22 is typically secured to the central column 16.

[0008] The position of the actuator 22 behind and on the legrest assembly 14 provides a bulky assembly. The actuator 22 adds weight to the legrest assembly 14. As such, when moving the legrest assembly 14, the actuator 22 uses energy sufficient to move both the legrest assembly 14 and the actuator 22 itself. The added weight and bulk, as well as the center of gravity, may cause adjustment of the legrest assembly to be uneven and halting.

[0009] Figure 3 illustrates an isometric side view of the conventional power wheelchair 10 in which the legrest assembly 14 is outwardly adjusted. As shown in Figure 3, the actuator 22, which is attached to the legrest assembly 14, moves the legrest assembly 14 and the actuator 22 in the direction of arc A. The legrest assembly 14 pivotally moves in the direction of arc A about a hinged interface that connects the legrest assembly 14 to the seat assembly 12. An individual may adjust the legrest assembly 14 through various positions, such as through a control interface.

[0010] As shown in Figures 1-3, the central column 16 of the legrest assembly 14 is straight. When the legrest assembly 14 is adjusted upwardly in the direction of arc A, the straight central column 16 typically causes the force of the weight of the individual legs to concentrate onto the heels that are supported by the footrests 20. As the legrest assembly 14 continues to move upward in the direction of arc A, the concentration of the weight on the heels typically increases, which may cause the individual seated in the wheelchair to experience discomfort.

[0011] Additionally, conventional wheelchair assemblies such as shown in Figures 1- 3 provide a limited range of adjustability. Also, in order to adjust the length of the individual legrests of the legrest assembly 14, a separate and distinct mechanism, such as a hinge mechanism 24 positioned behind each legrest is used. However, the hinge mechanism 24 on each legrest adds even more weight and bulk to the legrest assembly 14.

SUMMARY OF EMBODIMENTS OF THE INVENTION

[0012] Certain embodiments of the present invention provide a wheelchair that includes a seat assembly configured to support an individual, a curved legrest assembly pivotally connected to the seat assembly, and an adjustment assembly configured to adjust the curved legrest assembly through a range of motion. The adjustment assembly may include an actuator operatively connected to the curved legrest assembly through a piston slidably secured within a sleeve. The adjustment assembly is secured underneath the seat assembly.

[0013] The legrest assembly may include a curved central column secured to curved legrest beams. The curved central column may include a first or male beam slidably secured to a second or female beam.

[0014] The curved central column is adjustably secured to the curved legrest beams through an extension bracket that allows for each of the curved central column and the curved legrest beams to be independently adjusted with respect to one another.

[0015] The extension bracket may include a central channel and two lateral channels. The curved legrest beams may be adjustably secured within the lateral channels, and the central column may be adjustably secured within the central channel. Each of the central channel and the lateral channels may connect to at least one threaded bore configured to receive a set screw. The set screws may be selectively tightened and loosened to adjust the curved legrest beams with respect to one another and the central column. Further, the extension bracket may be adjusted with respect to the central column in a like manner.

[0016] The wheelchair may also include a bracing bracket having a curved track secured underneath the seat assembly. The central column may connect to the bracing bracket through a rolling bracket having rollers abutting the curved track. The rolling bracket may be spring-biased with respect to the central column.

[0017] Certain embodiments of the present invention provide a legrest assembly for a wheelchair. The legrest assembly includes a curved central column having an end configured to be pivotally connected to a seat assembly of the wheelchair, a first curved legrest beam secured to one side of the curved central column, and a second curved legrest beam secured to an opposite side of the curved central column. The curve of each legrest beam may be aligned and consistent with that of the central column.

[0018] The curved central column may include a male beam slidably secured to a female beam. The first and second curved legrest beams may be secured to the female beam.

[0019] The legrest assembly may also include an extension bracket adjustably secured to each of the curved central column and the first and second curved legrest beams. The extension bracket secures the first and second curved legrest beams to the curved central column. The extension bracket allows for each of the curved central column and the first and second curved legrest beams to be independently adjusted with respect to one another.

[0020] The extension bracket may include a central channel and first and second lateral channels. The first and second curved legrest beams may be adjustably secured within the first and second lateral channels, respectively. The central column is adjustably secured within the central channel. Each of the central channel and the first and second lateral channels connects to at least one threaded bore configured to receive a set screw.

[0021] Certain embodiments of the present invention provide a powered wheelchair that includes a support base having wheels, a seat assembly supported by the support base, a curved legrest assembly, and an adjustment assembly. The curved legrest assembly is pivotally connected to the seat assembly. The curved legrest assembly includes (i) a curved central column having an end configured to be pivotally connected to a seat assembly of the wheelchair, (ii) a first curved legrest beam secured to one side of the curved central column, (iii) a second curved legrest beam secured to an opposite side of the curved central column, and (iv) an extension bracket adjustably secured to each of the curved central column and the first and second curved legrest beams. The extension bracket secures the first and second curved legrests to the curved central column. The extension bracket allows for each of the curved central column and the first and second curved legrest beams to be independently adjusted with respect to one another.

[0022] The adjustment assembly may include an actuator operatively connected to the central column through a piston slidably secured within a sleeve. The adjustment assembly may be secured underneath the seat assembly.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0023] Figure 1 illustrates an isometric side view of a conventional power wheelchair.

[0024] Figure 2 illustrates an isometric front view of a conventional power wheelchair.

[0025] Figure 3 illustrates an isometric side view of a conventional power wheelchair in which a legrest assembly is outwardly adjusted.

[0026] Figure 4 illustrates a front view of a power wheelchair, according to an embodiment of the present invention. [0027] Figure 5 illustrates a side view of a power wheelchair, according to an embodiment of the present invention.

[0028] Figure 6 illustrates a side view of a power wheelchair in which a legrest assembly is outwardly adjusted, according to an embodiment of the present invention.

[0029] Figure 7 illustrates a side view of a legrest assembly connected to a seat assembly, according to an embodiment of the present invention.

[0030] Figure 8 illustrates an isometric bottom view of a legrest assembly connected to a seat assembly, according to an embodiment of the present invention.

[0031] Figure 9 illustrates an isometric front view of a legrest assembly, according to an embodiment of the present invention.

[0032] Figure 10 illustrates an isometric front view of an extension bracket, according to an embodiment of the present invention.

[0033] Figure 11 illustrates an isometric front view of a legrest assembly, according to an embodiment of the present invention.

[0034] Figure 12 illustrates a side view of a legrest assembly adjusted outwardly with legrest beams extended, according to an embodiment of the present invention.

[0035] Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0036] Figure 4 illustrates a front view of a power wheelchair 40, according to an embodiment of the present invention. The wheelchair 40 includes a support base 42 having wheels 44. The support base 42 supports a seat assembly 46. A legrest assembly 48 pivotally connects to the seat assembly 46. [0037] Figure 5 illustrates a side view of the power wheelchair 40. The legrest assembly 48 includes a central column 50 having a proximal end 52 that secures to a pivot bracket 54 that connects to the seat assembly 46.

[0038] The central column 50 is secured to legrest beams 56 through an extension bracket 58. Distal ends of the legrest beams 56 are connected to footrests 60.

[0039] Unlike the conventional wheelchair, the central column 50 and the legrest beams 56 are curved. The central column 50 and the legrest beams 56 generally bow out from proximal ends (closest to the seat assembly 46) and arc back from the bowed out area toward distal ends (closest to the footrests). Thus, the centers of the central column 50 and the legrest beams 56 may bow out to a greater extent than the ends of the respective central column 50 and the legrest beams 56.

[0040] Because the legrest assembly 48 is curved, as described above, the legrest assembly 48 moves along an arc as it rotates about the seat assembly 46. It has been found that the curved nature of the legrest assembly 48 adjusts the position of the footrests 60 during movement, which relieves pressure on an individual's heels as the legrest assembly 48 pivots outwardly from the seat assembly 46.

[0041] Figure 6 illustrates a side view of the power wheelchair 40 in which the legrest assembly 48 is outwardly adjusted. An individual may operate the wheelchair 40 to adjust the legrest assembly 48 through a range of motion such as along arc B. As shown in Figure 6, for example, the curve of the central column 50 may be evenly and consistently aligned and in conformity with the curve of each legrest beam 56. That is, the legrest beams 56 connect to the central column such that an even and contiguous curve ranges over the entire length from the central column 50 to the ends of the legrest beams 56.

[0042] Figure 7 illustrates a side view of the legrest assembly 48 connected to the seat assembly 46, according to an embodiment of the present invention. The proximal end 52 of the central column 50 pivotally connects to the seat assembly 46 through the pivot bracket 54. The pivot bracket 54, in turn, connects to an axle (not shown in Figure 7), which, in turn, connects to a link 62. The link 62 connects to a distal end of a piston 64 that is slidably secured within a sleeve 66. The piston 64 is configured to slide into and out of the sleeve 66 by way of an actuator 68. Movement of the piston 64 may be controlled through hydraulics, pneumatics, or the like. [0043] As shown in Figure 7, the actuator 68 is secured underneath the seat assembly 46, instead of behind and on the legrest assembly 48. Thus, the legrest assembly 48 is lighter and less bulky than that of the conventional wheelchair 10 (shown in Figures 1-3).

[0044] Figure 8 illustrates an isometric bottom view of the legrest assembly 48 connected to the seat assembly 46. The central column 50 may include a male beam 70 that may be adjusted with respect to a female beam 72. That is, the male beam 70 may fit within a channel within the female beam 72, and the female beam 72 may be adjusted for length with respect to the male beam 70.

[0045] A clamp 74 configured for receiving a web belt (not shown) that operatively connects to a rolling bracket 86 allows the female beam 72 to slide outwardly from the male beam 70. Optionally, the central column 50 may be a single unitary beam.

[0046] In any event, the proximal end 52 of the central column 50 secures to an axle 76 that is rotatably secured by opposing brackets 78 underneath the seat assembly 46. Optionally, the central column 50 may be integrally formed with the axle 76. The link 62 secures to the pivot bracket 54, which is secured to the central column 50 and/or the axle 76. Thus, when the actuator 68 (not shown in Figure 8) moves the piston 64, the axle 76 and the central column 50 move in response to adjust the position of legrest assembly 48.

[0047] A stud 80 extends beneath the central column 50 proximate the union with the axle 76. The stud 80 includes a spring 82 secured around a pin 86 that connects the stud 80 to a rolling bracket 88. The rolling bracket 88 includes wheels or rollers 90 at an end that is distally located from the pin 86. The rollers 90 are positioned within a curved track 92 of a bracing bracket 94. In an alternative embodiment, the wheelchair 40 may not include the stud 80, the rolling bracket 88 and the bracing bracket 94.

[0048] As the legrest assembly 48 moves outwardly from the seat assembly 46, the piston 64 pivots the central column 50 about the axle 76. As such, the rolling bracket 88 moves through the curved track 92 toward the axle 76. The spring 82, which is operatively connected to the rolling bracket 88, responsively resists and keeps the rollers 90 within the curved track 92 at all positions along the curved track 92. Consequently, the rolling bracket 88 pivots with respect to the stud 80 about the pin 86. Accordingly, the rolling bracket 88 provides bracing support to the legrest assembly 48 as the legrest assembly 48 moves. When the legrest assembly 48 moves back to its original position, the spring 82 ensures that the rollers 90 remain in the curved track 92. [0049] A web belt (not shown), which may be formed of plastic, an elastomeric material, flexible metal, or the like, may be secured to the rolling bracket 88. The web belt may pass around the axle of the rollers 90. The web belt may also connect to the clamp 74. For example, the web belt may pass through the two aligned slots 89 formed through the clamp 74.

[0050] As the rollers 90 move, the rollers 90 adjust the tension in the web belt, allowing the female beam 72 to extend from the male beam 70 as tension is released, or pulling the female beam 72 onto the male beam 70 as tension is increased. In this manner, the web belt may allow for variable length of the female beam 72 with respect to the male beam 70.

[0051] Figure 9 illustrates an isometric front view of the legrest assembly 48, according to an embodiment of the present invention. The central column 50 securely connects to legrest beams 56 through the extension bracket 58.

[0052] Figure 10 illustrates an isometric front view of the extension bracket 58, according to an embodiment of the present invention. The extension bracket 58 includes a main body 89 having a central channel 91 and lateral channels 93 formed therethrough. A plurality of threaded bores 96 are formed through the main body 89 and connect to the channels 91 and 93. For example, as shown in Figure 10, outer bores 96 connect to the lateral channels 93 while inboard bores 96 connect to the central channel 91.

[0053] The threaded bores 96 are configured to receive and threadably retain set screws (not shown). The set screws are used to adjust the central column 50 and the legrest beams 56 within the central and lateral channels 91 and 93, respectively.

[0054] Referring to Figures 9 and 10, the central column 50 passes through the central channel 91, while the legrest beams 56 pass through the lateral channels 93. To secure the central column 50 and the legrest beams 56 in position, set screws within the threaded bores 96 are engaged and abut into the central column 50 and legrest beams 56, thereby securing them in position.

[0055] The extension bracket 58 allows for individual adjustment of legrest beams 56 with respect to the central column 50. Additionally, the extension bracket 58 may be adjusted with respect to the central column 50. That is, the set screws that engage the central column 50 may be loosened so that the extension bracket 58 may be slid up or down the central column 50 to a desired position, at which point the set screws may be tightened to secure the extension bracket 58 in place. Similarly, each legrest beam 56 may be individually adjusted with respect to the extension bracket 58.

[0056] Thus, the extension bracket 58 allows for separate and independent adjustment of the legrest beams 56 and the central column 50. Moreover, the extension bracket 58 provides a simple and light system for adjustment that does not significantly add weight and bulk to the legrest assembly 48.

[0057] Figure 11 illustrates an isometric front view of the legrest assembly 48. As shown in Figure 1 1, a removable cover 98 may be positioned on the extension bracket 58. The cover 98 is positioned over a cavity in which the threaded bores 96 (shown in Figures 9 and 10) are located. The cover 98 may be secured to the extension bracket 58 through separate fasteners, or the cover 98 may snapably secure to the extension bracket 58.

[0058] Figure 12 illustrates a side view of the legrest assembly 48 adjusted outwardly with legrest beams 56 extended, according to an embodiment of the present invention. In this position, the legrest beams 56 have been slidably extended with respect to the extension bracket 58. As noted above, the legrest beams 56 may be adjusted with respect to the extension bracket 58, and the extension bracket 58 may be slidably adjusted over the length of the central column 50 to accommodate a wide range of lengths. Additionally, as noted above, the curved nature of the legrest assembly 48 reduces the concentration of the weight of an individual's heels into the footrests 60.

[0059] Thus, embodiments of the present invention provide a legrest assembly for a wheelchair. Unlike the conventional wheelchair shown in Figures 1-3, the actuator is positioned underneath the seat assembly. Accordingly, the legrest assembly is less bulky.

[0060] Further, the curved nature of the legrest assembly provides for increased comfort, as compared to the straight legrests of conventional wheelchairs.

[0061] Additionally, the simple, efficient, and light extension bracket allows for length adjustment of the legrest assembly. The extension bracket provides a lighter and less bulky legrest assembly as compared to the conventional wheelchair shown and described with respect to Figures 1-3.

[0062] Overall, it has been found that embodiments of the present invention provide a legrest assembly for a powered wheelchair that slides more smoothly and over a greater range than conventional wheelchairs, due to the curved nature of the legrest assembly and the actuator underneath the seat assembly. Additionally, embodiments of the present invention provide a lighter legrest assembly as compared to conventional wheelchairs. Moreover, it has been found that embodiments of the present invention provide a stronger and more stable legrest assembly. As noted above, embodiments of the present invention also provide a legrest assembly that reduces pressure on an individual's feet, as compared to prior wheelchairs.

[0063] Also, embodiments of the present invention provide a fully-adjustable legrest assembly that is simpler than previous legrest assemblies. That is, embodiments of the present invention provide a legrest assembly with less parts and simpler operation as compared to prior wheelchairs.

[0064] While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like, may used to describe embodiments of the present invention, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.

[0065] Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

[0066] Various features of the invention are set forth in the following claims.