Wood chipper with optimized production control

Abstract

A drum-type wood chipper for processing wood includes a chipper drum that is adapted to rotate about a generally horizontal drum axis, a plurality of cutting blades that are disposed around the periphery of the chipper drum, and an engine that is adapted to rotate the chipper drum about the drum axis. The wood chipper also includes a feed system that is adapted to advance wood to be processed towards the chipper drum, and a controller that is operatively connected to the engine and adapted to determine an instantaneous engine operating rate during rotation of the chipper drum. The controller is also operatively connected to the feed system and adapted to control the rate of advance of wood towards the chipper drum. The controller is also adapted to modify the rate of advance of wood towards the chipper drum as the instantaneous engine operating rate changes while the chipper drum is being rotated.

Claims

1. A drum-type wood chipper for processing wood, said wood chipper comprising: a) a chipper drum assembly comprising: i) a chipper drum having a chipper drum radius, said chipper drum being adapted to rotate about a generally horizontal drum axis; ii) an engine that is adapted to rotate the chipper drum about the drum axis; iii) a plurality of cutting blades that are disposed around the periphery of the chipper drum, said plurality of cutting blades having leading edges that define a chipping arc of rotation as the chipper drum rotates, said chipping arc of rotation having a radius that is larger than the chipper drum radius by a predetermined amount; b) a feed system having a feed conveyor for advancing wood to be processed towards the plurality of cutting blades of the chipper drum; c) a controller that is: i) adapted to receive a maximum engine operating rate, a minimum engine operating rate, and an intermediate engine operating rate that is between the maximum engine operating rate and the minimum engine operating rate; ii) operatively connected to the engine and adapted to determine an instantaneous engine operating rate during rotation of the chipper drum; iii) operatively connected to the feed system and adapted to control a rate of advance of wood towards the chipper drum; iv) adapted to modify a linear speed of the feed conveyor in a first direction advancing wood towards the chipper drum in response to changes in the instantaneous engine operating rate while the chipper drum is being rotated; (v) adapted to cause the linear speed of the feed conveyor in the first direction to decline at a first rate of decline as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate; and (vi) adapted to cause the linear speed of the feed conveyor in the first direction to decline at a second rate of decline that is greater than the first rate of decline as the engine operating rate decreases from the intermediate engine operating rate and without changing the direction of the feed conveyor.

2. The drum-type wood chipper of claim 1 wherein: a) the feed system includes a feed conveyor having a feed conveyor drive system; b) the controller is: i) operatively connected to an engine sensor for determining the instantaneous operating rate of the engine; ii) operatively connected to a feed rate sensor for determining the linear speed of the feed conveyor; iii) operatively connected to the drive system for the feed conveyor; iv) adapted to modify the linear speed of the feed conveyor as the instantaneous engine operating rate changes while the chipper drum is being rotated.

3. The drum-type wood chipper of claim 1 wherein the controller is adapted to: a) determine a grinding mode rate of decline of the linear speed of the feed conveyor as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum operating rate; b) determine a chipping mode rate of decline of the speed of the feed conveyor as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum engine operating rate; c) cause the linear speed of the feed conveyor to decline at the chipping mode rate of decline as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate; d) cause the linear speed of the feed conveyor to decline at a rate that is greater than the chipping mode rate but less than the grinding mode rate as the engine operating rate decreases from the intermediate engine operating rate.

4. The wood chipper of claim 1 wherein the controller is adapted to operate the feed system at a feed rate of zero once the engine operating rate is less than the minimum engine operating rate.

5. A method of operating a drum-type wood chipper for processing wood, said method comprising the steps of: a) providing a chipper drum assembly including a chipper drum having a chipper drum radius, said chipper drum being adapted to rotate about a generally horizontal drum axis; b) providing an engine that is adapted to rotate the chipper drum about the drum axis; c) providing a plurality of cutting blades around the periphery of the chipper drum, said plurality of cutting blades having leading edges that define a chipping arc of rotation as the chipper drum rotates, said chipping arc of rotation having a radius that is larger than the chipper drum radius by a predetermined amount; d) providing a feed system that advances wood to be processed towards the chipper drum, said feed system including a feed conveyor having a feed conveyor drive system; e) providing a feed rate sensor for determining an instantaneous rate of advance of wood towards the chipper drum as the feed conveyor drive system is operated; f) providing an engine sensor for determining an instantaneous operating rate of the engine as the chipper drum is rotated; g) providing a controller that is: i) operatively connected to the engine sensor and adapted to determine an instantaneous engine operating rate during operation of the engine to rotate the chipper drum; ii) operatively connected to the feed conveyor drive system and adapted to control the rate of advance of wood towards the chipper drum; iii) adapted to modify the linear speed of advance of wood towards the chipper drum depending on the instantaneous engine operating rate while the engine is being operated to rotate the chipper drum; h) operating the controller to modify the rate of advance of wood towards the chipper drum as the instantaneous engine operating rate changes while the chipper drum is being rotate; i) providing a controller interface that is operatively connected to the controller; j) entering a maximum engine operating rate, minimum engine operating rate, and intermediate engine operating rate into the controller via the controller interface; k) operating the controller to cause the speed of the feed system to decline at a first rate of decline as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate; l) operating the controller to cause the speed of the feed system to decline at a second rate of decline that is greater than the first rate to a non-zero speed as the engine operating rate decreases from the intermediate engine operating rate and without changing the direction of the feed conveyor.

6. The method of claim 5 which includes: a) providing a controller that is adapted to: i) determine a grinding mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum engine operating rate; ii) determine a chipping mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum engine operating rate; b) operating the controller so as to: i) cause the speed of the feed system to decline at the chipping mode rate of decline as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate; ii) cause the speed of the feed system to decline at a rate that is greater than the chipping mode rate but less than the grinding mode rate as the engine operating rate decreases from the intermediate engine operating rate.

7. The method of claim 5 further comprising the step operating the feed conveyor at a feed rate of zero once the engine operating rate is less than the minimum engine operating rate.

8. A method of operating a drum-type wood chipper for processing wood, said method comprising the steps of: a) providing a chipper drum assembly having a chipper drum with a plurality of cutting blades; b) rotating the chipper drum with an engine; c) advancing wood to be processed towards the plurality of cutting blades of the chipper drum with a feed conveyor of a feed system; d) determining an instantaneous rate of advance of the wood towards the chipper drum (feed rate) with a feed rate sensor; e) determining an instantaneous engine operating rate of the engine (engine operating rate) with an engine sensor as the chipper drum is rotated; f) providing a controller that is operatively connected to the feed system and engine and is configured to receive the engine operating rate and to control the feed rate; g) inputting a maximum engine operating rate, minimum engine operating rate, and intermediate engine operating rate into the controller via an controller interface; h) modifying the feed rate with the controller based on the instantaneous engine operating rate, wherein the controller causes the feed rate to decline at a first rate of decline as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate and to decline at a second rate of decline that is greater than the first rate of decline to a non-zero feed rate without changing the direction of the feed conveyor as the engine operating rate decreases from the intermediate engine operating rate.

9. The method of claim 8 further comprising the steps: a) maintaining the feed rate at the second rate of decline as the engine operating rate decreases from the intermediate engine operating rate to the minimum engine operating rate; and b) modifying the feed rate with the controller to zero without changing the direction of the feed conveyor to stop the wood from advancing further towards the chipper drum once the engine operating rate is below the minimum engine operating rate.

10. The method of claim 8 further comprising the steps of: a) determining a grinding mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum engine operating rate; b) determine a chipping mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the minimum engine operating rate; c) setting the first rate of decline equal to the chipping mode rate of decline with the controller as the engine operating rate decreases from the maximum engine operating rate to the intermediate engine operating rate; d) setting the second rate of decline greater than the chipping mode rate and less than the grinding mode rate as the engine operating rate decreases from the intermediate engine operating rate.

11. The method of claim 8 wherein the first rate of decline is proportional with a rate of decrease of the engine operating rate as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the intermediate engine operating rate.

12. The method of claim 11 wherein the second rate of decline is not proportional with the rate of decrease of the engine operating rate as the engine operating rate decreases during operation of the wood chipper from the intermediate engine operating rate.

13. The method of claim 8 further comprising the step of modifying the feed rate with the controller to zero once the engine operating rate is less than the minimum engine operating rate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The presently preferred embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and wherein:

(2) FIG. 1 is a perspective view of a drum-type wood chipper that may be operated according to the invention.

(3) FIG. 2 is a schematic sectional view of a portion of the chipper drum assembly and certain components of the feed system that are adapted to advance wood to be processed towards the chipper drum, showing a log that is positioned for operation of the wood chipper in chipping mode.

(4) FIG. 3 is an exemplary graphical representation of the operation of a drum-type wood chipper in chipping mode.

(5) FIG. 4 is a schematic sectional view of a portion of the chipper drum assembly and certain components of the feed system that are adapted to advance wood to be processed towards the chipper drum, showing a log that is positioned for operation of the wood chipper in grinding mode.

(6) FIG. 5 is an exemplary graphical representation of the operation of a drum-type wood chipper in grinding mode.

(7) FIG. 6 is an exemplary graphical representation of the operation of a drum-type wood chipper according to a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(8) This description of preferred embodiments of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale, and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness.

(9) As shown in FIGS. 1, 2 and 4, a preferred embodiment of the invention comprises a drum-type wood chipper 10 which includes trailer 12 that is adapted to be pulled by a tractor or other vehicle. Trailer 12 includes frame 14 that is supported by wheels 16 and a pair of adjustable support legs, one of which, support leg 18, is shown in FIG. 1. In other embodiments of the invention, the wood chipper can be mounted on a self-propelled frame or chassis, or on a fixed frame. Supported on frame 14 of trailer 12 are feed chute 20 and a chipper drum assembly that is partially enclosed by chipper drum housing 22. Accelerator wheel housing 26 houses an accelerator wheel (not shown) downstream of chipper drum housing 22, and discharge chute 28 is located downstream of the accelerator wheel. Other embodiments of the invention omit the accelerator wheel and its housing, and locate the discharge chute adjacent to the chipper drum assembly.

(10) The chipper drum assembly includes chipper drum 30 that is mounted for rotation (in the counter-clockwise direction, as shown in FIGS. 2 and 4) about generally horizontal drum axis A.sub.D. Chipper drum 30 includes circumferential wall 31 defining chipper drum radius R.sub.D, and a plurality of pockets 32 that are spaced around the periphery of chipper drum 30 within circumferential wall 31. A plurality of cutting blades 34, each of which has a leading edge 35, are disposed around the periphery of chipper drum 30.

(11) In the embodiment of the invention illustrated in the drawings, a cutting blade 34 is mounted on each of the pockets so that as chipper drum 30 rotates, the leading edges 35 of the plurality of cutting blades 34 define a chipping arc of rotation A.sub.C that is parallel to circumferential wall 31 and has a larger radius than the radius R.sub.D of the circumferential wall. Consequently, chipping arc of rotation Ac has a radius R.sub.C that is larger than the chipper drum radius R.sub.D by a predetermined amount R.sub.P, as can be seen in FIG. 2.

(12) A feed system is provided to advance wood to be processed towards chipper drum 30. As shown in FIGS. 2 and 4, the preferred feed system includes feed conveyor 36 and compression roller 37. In this embodiment of the invention, compression roller 37 is mounted on pivotal arm 38, which is adapted to pivot about pivot axis A.sub.P with respect to the frame of wood chipper 10. Compression roller 37 is adapted to be urged generally downwardly towards feed conveyor 36 and cooperates with feed conveyor 36 to align and urge a log such as log 40 towards chipper drum 30.

(13) Engine 41 is also mounted on frame 14 of wood chipper 10, and is adapted to provide a rotational force to chipper drum 30 within chipper drum housing 22 by means of one or more drive belts or other conventional drive transfer mechanisms (not shown). In the embodiment of the invention illustrated in the drawings, engine 41 is also adapted to provide a rotational force to the accelerator wheel within accelerator wheel housing 26, which rotates in the same direction as chipper drum 30 by means of one or more drive belts or other conventional drive transfer mechanisms (not shown). The accelerator wheel acts to increase the momentum of chips produced by chipper drum 30 into (and out of) discharge chute 28 along discharge path 46.

(14) Controller interface 48 is provided by which an operator may enter operating parameters for wood chipper 10 into controller 50. Controller 50 may embody a single microprocessor or multiple microprocessors that include components for controlling operations of wood chipper 10 based on input from an operator of the wood chipper and on sensed or other known operational parameters. Controller 50 may include a memory, a secondary storage device, a processor and other components for running an application. Various other circuits may be associated with controller 50 such as power supply circuitry, sensor signal circuitry, signal conditioning circuitry, solenoid driver circuitry and other types of circuitry. Numerous commercially available microprocessors can be configured to perform the functions of controller 50. It should be appreciated that controller 50 could readily be embodied in a general purpose computer or machine microprocessor capable of controlling numerous machine functions.

(15) Controller 50 is operatively connected to engine sensor 51 (shown in FIG. 1) for determining the instantaneous operating rate of engine 41. Controller 50 is operatively connected to feed rate sensor 52 (shown in FIGS. 2 and 4) or to another sensor (not shown) for determining the linear speed of conveyor 36. Controller 50 is also operatively connected to a conventional drive system for feed conveyor 36 and is adapted to modify the linear speed of the feed conveyor. Controller 50 may also be operatively connected to engine 41 and adapted to modify the rotational speed of the cutting drum by modifying the engine operating rate.

(16) Examples of information that may be input into controller 50 by an operator through controller interface 48 are the chipper drum radius R.sub.D, the number and spacing of cutter blades mounted on the chipper drum, and the measured gap R.sub.P between the chipper drum radius R.sub.D and the chipping arc of rotation radius R.sub.C. The operator may also enter a maximum engine operating rate and a minimum engine operating rate, and the beginning rate of advance of wood to the chipper drum. In some embodiments of the invention, the operator may enter a desired relationship, in the form of a ratio or a formula, between the rate of advance of wood towards the chipper drum (i.e., the speed of the feed conveyor) and the engine operating rate.

(17) A wood chipper such as wood chipper 10 may be operated in a chipping mode in order to produce chips of a uniform size, without attempting to maximize an overall production rate. FIG. 2 illustrates the presentation of log 40 to chipping drum 30 according to a chipping mode of operation. In carrying out a chipping mode of operation, certain operating parameters must be strictly controlled, including the rotational speed of the chipper drum (which is based in part on the number and spacing of cutting blades mounted around the periphery of the chipper drum and the size of the gap R.sub.P between the chipper drum radius R.sub.D and the chipping arc of rotation radius R.sub.C) and the rate of advance of wood to be chipped to the chipper drum. However, as has been described hereinabove, the presentation of a log to the chipper drum for the cutting of chips causes resistance that reduces the rate of rotation of the chipper drum and increases the load on the engine. The amount of resistance generated depends primarily on the rate of advance of the wood to the chipper drum. If this resistance is significant, the engine will not be able to maintain the desired rotational speed of the chipper drum, and the chipper drum will slow. When a wood chipper is operated in a chipping mode, as shown in an exemplary embodiment in FIG. 3, the operator can attempt to reduce the rate of advance of the wood to be chipped proportionally to the rate of reduction of the engine operating rate for the portion of the operating cycle indicated by line segment 53, in order to maintain the desired chip size. Thus, for example, FIG. 3 illustrates a chipping mode method of control, wherein the maximum (or beginning) engine operating rate is set at 2150 rpm, and the beginning rate of advance of wood to the chipper drum is set at 108 ft/min. As shown in FIG. 3, a wood chipper may be operated so that the rate of advance of wood to the chipper drum falls in response to the rate of reduction of the engine operating rate from the initial rate of 108 ft/min. at the beginning engine operating rate, in a linear fashion represented by line segment 53 according to the formula y=0.05x (where y is the feed speed in ft/min. and x is the engine operating rate in rpm) to 80 ft/min at the minimum engine operating rate of 1600 rpm, which is the rate at which the advance of wood to the chipper drum is stopped in order to avoid stalling of the engine. This stoppage of the advance of wood to the chipper drum is characteristic of a chipping mode of operation, since reducing the rate of advance of wood to the chipper drum is not always effective to maintain uniform chip size when the load imposed on the engine by resistance occurs suddenly or is particularly large. This stoppage of the advance of wood to the chipper drum when the operating rate of the engine falls to the predetermined limit of 1600 rpm is indicated by line segment 54 of FIG. 3. Thereafter, when the engine, operating under reduced load, recovers to an operating rate that provides an acceptable rate of rotation of the chipper drum, the operator may operate the feed system to resume the advance of the wood to the chipper drum.

(18) A wood chipper such as wood chipper 10 may also be operated in a grinding mode in order to maximize an overall production rate and avoid engine stalling. FIG. 4 illustrates the presentation of log 40 to chipping drum 30 according to a grinding mode of operation. By comparing the position of log 40 with respect to the chipping drum in FIG. 4 with the position of the log to the chipping drum as shown in FIG. 2, the difference in presentation between a chipping mode of operation and a grinding mode of operation can be appreciated. When operating in a grinding mode, the rate of advance of wood to the chipper drum is reduced at a greater rate than the rate of reduction of the rotational speed of the chipper drum that is caused by resistance. This method of operation will insure that the engine will not stall; however, chips produced using this method will not be uniform in size, even though the overall production quantity will be increased over what may be obtained using a chipping mode of operation. When a wood chipper is operated in a grinding mode, as shown in an exemplary embodiment in FIG. 5, the rate of advance of the wood to be chipped is reduced at a greater rate than the rate of reduction of the engine operating rate for the operating cycle indicated by line segment 56, in order to avoid engine stalling. Thus, for example, FIG. 5 illustrates a grinding mode method of control, wherein the maximum (or beginning) engine operating rate is set at 2150 rpm, and the beginning rate of advance of wood to the chipper drum is set at 108 ft/min. As shown in FIG. 5, the rate of advance of wood to the chipper drum is reduced from the initial rate of 108 ft/min. at the beginning engine operating rate, in a linear fashion represented by line segment 56 according to the formula y=0.194x310 (where y is the feed speed in ft/min. and x is the engine operating rate in rpm) to 0 ft/min at the minimum engine operating rate of 1600 rpm. This mode of operation maximizes the overall production rate of the wood chipper, but does not result in the production of chips of uniform size.

(19) The preferred embodiment of the invention comprises a controller and control method for a wood chipper which allows operation at a higher production rate than a machine operating in a typical chipping mode, while maintaining relative chip size uniformity at a much greater level than could be obtained from operation in a typical grinding mode. The controller is adapted to monitor the instantaneous engine operating rate during rotation of chipper drum, and to modify the rate of advance of wood towards the chipper drum as the instantaneous engine operating rate changes while the chipper drum is being rotated. Preferably, the controller is adapted to modify the rate of advance of wood towards the chipper drum in order to maintain a desired relationship between the rate of advance of wood towards the chipper drum and the engine operating rate.

(20) Controller 50 is operatively connected to controller interface 48 and adapted to receive a predetermined maximum engine operating rate that is entered by the operator, a predetermined minimum engine operating rate and a predetermined intermediate engine operating rate between the predetermined maximum and the predetermined minimum rates. The intermediate engine operating rate for this control method is set by the operator so as to account for field conditions and wood type and to optimize chip product uniformity and production rate according to desired production and chip uniformity requirements. Controller 50 is also adapted to receive a beginning rate of advance of the feed system that is entered by the operator

(21) In one embodiment of the invention, the controller is adapted to reduce the speed of the feed conveyor at a first rate as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to an intermediate engine operating rate, and at a second rate which is greater (i.e., steeper) than the first rate as the engine operating rate decreases from the intermediate engine operating rate. In this embodiment of the invention, the controller is adapted to reduce the speed of feed conveyor 36 at a first rate as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the intermediate engine operating rate, as illustrated by line segment 58 of FIG. 6, and at a second rate which is greater (i.e., steeper) than the first rate as the engine operating rate decreases from the intermediate engine operating rate (indicated at 59 in FIG. 6), as illustrated by line segment 60 of FIG. 6.

(22) In one embodiment of the invention, the controller monitors the instantaneous engine operating rate during rotation of chipper drum 30, and causes the speed of the feed system to decline at a calculated chipping mode rate of decline as the resistance-induced decline in the rotational speed of the chipper drum causes the engine operating rate to decrease from the maximum engine operating rate to a predetermined intermediate engine operating rate, and it causes the speed of the feed system to decline at a rate that is greater than the chipping mode rate but less than a calculated grinding mode rate as the engine operating rate decreases from the intermediate engine operating rate. In this mode of operation, the advance of wood to the chipper drum does not cause the engine to stall except under the most severe conditions. Operation of a wood chipper according to this control method allows for a high production rate with a limited amount of non-uniformly sized chips. The small compromise in chip uniformity is offset by higher production than is obtained by a wood chipper operating in chipping mode.

(23) According to one embodiment of the invention, controller 50 is adapted to receive a predetermined maximum engine operating rate, such as, for example, 2150 rpm, that is entered by the operator, a predetermined minimum engine operating rate, such as for example, 1600 rpm, and a predetermined intermediate engine operating rate between the predetermined maximum and the predetermined minimum rates, such as for example, 1800 rpm. The intermediate engine operating rate for this control method may be set by the operator so as to take into consideration field conditions and wood type and to optimize chip product uniformity and production rate according to desired production and chip uniformity requirements. In this embodiment of the invention, controller 50 is also adapted to receive a beginning rate of advance of the feed system, such as, for example, 108 ft/min., that is entered by the operator. The controller is adapted to reduce the speed of feed conveyor 36 at a first rate as the engine operating rate decreases during operation of the wood chipper from the maximum engine operating rate to the intermediate engine operating rate, as illustrated by line segment 58 of FIG. 6, and at a second rate which is greater (i.e., steeper) than the first rate as the engine operating rate decreases from the intermediate engine operating rate (indicated at 59 in FIG. 6), as illustrated by line segment 60 of FIG. 6.

(24) In one embodiment of the invention, the controller is adapted to determine or calculate a chipping mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine rotation rate to the minimum engine rotation rate. Such a rate is illustrated by line segment 58 of FIG. 6, which is shorter than, but at the same slope as, line segment 53 of FIG. 3. The controller in this embodiment of the invention is also adapted to determine or calculate a grinding mode rate of decline of the speed of the feed system as the engine operating rate decreases during operation of the wood chipper from the maximum engine rotation rate to the minimum engine rotation rate. Such a rate is illustrated by line segment 56 of FIG. 5. Then, when the engine operating rate falls under load, the controller will cause the speed of the feed system to decline according to the calculated chipping mode of operation, to the predetermined intermediate rate of 88 ft/min. as indicated by point 59 of FIG. 6. The controller will thereafter cause the speed of the feed system to decline at a rate that is greater than the calculated chipping mode rate but less than the calculated grinding mode rate as the engine operating rate decreases from the intermediate engine rotation rate. Such a rate of decline of the feed conveyor as the engine operating rate decreases is illustrated by line segment 60 of FIG. 6. Its slope may be compared to that of line 54 of FIG. 3 and that of line segment 56 of FIG. 5.

(25) Although this description contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of the presently preferred embodiment thereof, as well as the best mode contemplated by the inventors of carrying out the invention. The invention, as described herein, is susceptible to various modifications and adaptations, as would be understood by those having ordinary skill in the art to which the invention relates.