Abstract:
A mobile floor cleaning machine has a clean water system with a reservoir for applying water to a floor during cleaning. The floor cleaning machine includes an ozone source which generates ozone in liquid form and introduces the liquid ozone directly into the circulating water for eliminating pathogens in the circulating water. The ozone is generated continuously and essentially instantaneously by the ozone source and destroys most bacteria, virus, fungus and mold in the circulating water at room temperature, while decaying harmlessly to oxygen within the water and producing fewer by-products than chemical sanitizers and having essentially no environmental impact.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to mobile floor cleaning machines and is particularly directed to a self-contained arrangement for continuously purifying the circulating water used to clean a floor during on-the-go operation of the floor cleaning machine. 
       BACKGROUND OF THE INVENTION 
       [0002]    Ozone is a highly reactive substance which naturally occurs as a gas comprised of three bonded oxygen atoms. Common uses of ozone include the treatment of drinking and swimming pool water, the treatment of industrial waste, the bleaching of inorganic products such as clay, and as a disinfectant. Ozone is formed by breaking apart diatomic oxygen molecules, with the free oxygen atoms thus produced reacting with conventional diatomic oxygen molecules to form ozone. In the past, two methods have been used to produce ozone for commercial purposes. These two methods involve ultraviolet (UV) radiation and corona discharge. Ultraviolet ozone generation has been used primarily in air ducts and for the preservation of food and is a relatively inefficient source of ozone. 
         [0003]    Corona discharge is on the order of 2½ times as efficient as ultraviolet light in terms of energy required to produce a corresponding amount of ozone and has been used to provide greater quantities and higher concentrations of ozone than UV light. Ozone is produced by corona discharge by positioning two parallel metal plate electrodes in relatively closely spaced relation and passing a high voltage alternating current through the two electrodes. Electrons traveling between the two electrodes collide with oxygen in the atmosphere to break apart the diatomic oxygen molecules, with the thus freed individual oxygen molecules reacting with the diatomic oxygen molecules to produce ozone. Although more energy efficient than the UV radiation approach to producing ozone, the corona discharge approach is also a relatively inefficient source of ozone and requires extensive safety provisions and complex installations because of the high voltages involved in this approach for ozone production. 
         [0004]    Ozone has been used in several applications to promote clean air and improve the atmosphere. For example, an ozonizer is disclosed as positioned in an exhaust duct of a vacuum cleaner to purify the exhaust air of the vacuum cleaner in U.S. Pat. No. 5,185,903. One problem that this approach arises from the propensity of ozone to act as a strong irritant causing discomfort to the eyes and throats of those in the vicinity of the ozone source. Higher concentrations of ozone are also believed to affect mental awareness and general health. 
         [0005]    Ozone is also disclosed for use in a circulating liquid cleaning solution for cleaning, sanitizing and deodorizing the application area in U.S. Pat. No. 7,302,733. However, in this approach, ozone is introduced in a gaseous state, with some of the ozone dissolved in the liquid cleaning solution, while some of the ozone remains in the gaseous state. Thus, this approach directly introduces ozone into the air and requires a carbon filter or an ultraviolet energy source in its exhaust system to limit the ozone concentration of its emissions. In addition, this approach uses the relatively inefficient approach of ultraviolet light generation of ozone which, as discussed above, is much less energy efficient than even the corona discharge approach to ozone generation. 
         [0006]    The present invention addresses the problems encountered in the prior art in the generation and use of ozone in mobile cleaning machines to provide a safe and economical approach to purifying the water in a mobile floor cleaning machine. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    Accordingly, it is an object of the present invention to continuously provide clean water in a self-contained manner for cleaning floors in a mobile floor cleaning machine. 
         [0008]    It is another object of the present invention to more efficiently clean with a mobile floor cleaning machine using a compact, self-contained, environmentally clean, economical, safe and energy efficient water purification system. 
         [0009]    It is yet another object of the present invention to use liquid ozone which is introduced directly into a circulating cleaning solution in a mobile cleaning machine for cleaning virtually any type of floor in a safe and economical manner. 
         [0010]    A further object of the present invention is to use ozone in liquid form to maintain a cleaning solution circulating in a closed system in a highly purified state by generating the ozone at its point of use to accommodate ozone&#39;s short half life, provide high efficiency of the ozone introduced into the cleaning solution, and avoid the technical and environmental challenges associated with ozone in the gaseous state. 
         [0011]    The present invention contemplates a floor cleaning machine comprising a vacuum nozzle located at a forward portion of the floor cleaning machine and adapted for suctioning material on a floor in front of the floor cleaning machine; a liquid cleaning solution reservoir; a floor scrubbing assembly including a scrub member disposed aft of the vacuum nozzle and including a contact portion adapted to contact the surface of a floor to be cleaned; a motor coupled to the scrub member for moving the scrub member into contact against the floor for scrubbing the floor; a fluid conveying system coupled to the liquid cleaning solution reservoir and to the scrub member for providing cleaning solution to the scrub member and further coupled to the vacuum nozzle for returning the cleaning fluid to the cleaning solution reservoir following use on the floor; and an ozone cell coupled to the fluid conveying system for injecting liquid ozone into the liquid cleaning solution for eliminating pathogens in the cleaning solution. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
           [0013]      FIG. 1  is a side view of a floor scrubbing machine for carrying out the present invention, but otherwise simplified, with the brush shown in vertical cross section, and with the brush in the raised or transport position; 
           [0014]      FIG. 2  is a view similar to  FIG. 1 , with the brush in the lowered or use position; 
           [0015]      FIG. 3  is a vertical sectional view showing the motor, drive hub and brush in vertical cross section (along a plane through the axis of rotation of the brush extending in the direction of travel) and with the motor shown diagrammatically; 
           [0016]      FIG. 4  is an upper perspective cross section view of the drive hub assembly; 
           [0017]      FIG. 5  is a view similar to  FIG. 4 , taken from a lower perspective of the drive hub; 
           [0018]      FIG. 6  is a circuit schematic diagram of the electrical control circuit for the machine of  FIG. 1  in the Transport Mode; 
           [0019]      FIG. 7  is an elevation view of the rear panel of a mobile floor cleaning machine for use in carrying out the present invention; 
           [0020]      FIG. 8  is a simplified side elevation view of a floor cleaning machine in accordance with the principles of the present invention; and 
           [0021]      FIG. 9  is a simplified sectional view of an ozone cell for use in the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Referring first to  FIG. 1 , reference numeral  10  generally designates a typical floor scrubbing machine for carrying out the present invention. The machine includes an outer housing or casing  11  and is supported by forward wheels  12 , as well as two rear caster wheels  13 . Some machines may only employ two wheels such as a carpet extractor. In addition, this invention can be used on very hard floors such as of hardwood, tile, concrete, etc., as well as on soft surfaces such as of plush carpeting or other soft material and can also be used on a wide range of floor textures. 
         [0023]    Within the housing  11  are batteries for powering the machine, a reservoir of cleaning fluid for application to the scrub brush or directly to the floor, with a rear suction device for recovering spent solution and a storage tank for tile spent solution, all of which are conventional and not shown in detail. While the floor scrubbing machine in the described embodiment is powered by batteries, it could equally as well be powered by an AC voltage source. However, this latter embodiment is not described for the sake of brevity and simplicity, as the cleaning machine could easily be adapted for AC operation by one skilled in the art. 
         [0024]    An operator&#39;s handle  16  is rigidly mounted to the frame permitting the operator to maneuver the machine. Forward of the handle  16  is an actuator  17 , controlled by the operator, which closes an Operator Run switch  17 A (See the schematic of  FIG. 6 ) when actuated. Actuator  17  may be a manually operated bail adjacent the operator&#39;s hand, and pivotally connected to the machine so that the operator can simply squeeze the pivoting actuator handle  17  toward the fixed handle  16  to actuate the Operator Run switch (to be further described within) and power the scrub brush in the lowered position of  FIG. 2 . 
         [0025]    Also mounted on the operator&#39;s console, adjacent the handle  16  (so as to be conveniently accessible to the operator) is a Keyswitch  18  (diagrammatically shown and designated  124  in the electrical schematic,  FIG. 6 ), which is a rotary switch temporarily actuated by a key and biased to an “off position, to be described further within. It will be appreciated, however, that the Keyswitch  18  is readily accessible to the operator when he or she is positioned at the operator&#39;s station behind the machine (to the right in  FIG. 1 ). 
         [0026]    Turning now to the lower forward portion of the machine, a scrub brush generally designated  20 , is mounted to a drive shaft connected to a motor  22 . At the lower end of the drive shaft (designated  34  in  FIG. 3 ) there is mounted a hub assembly generally designated  24 . The motor  22  is mounted above a deck  26  which houses the brush  20 . The motor and deck are carried by the frame of the machine  10  by means of a lift linkage in the form of a four-bar or parallel linkage generally designated  28 . A lever  29  provided with an actuating foot pedal  30  immediately in front of the operator&#39;s station is pivotally connected at  32  to the frame of the machine  10 . The forward end of the lever  29  forms the lower link of the four bar linkage  28  so that when the operator depresses the foot pedal  30 , the motor  22 , brush  20  and deck  26  are lifted to the raised position shown in  FIG. 1  for storage or transport. 
         [0027]    When the foot pedal  30  is released as seen in  FIG. 2 , the motor and brush are lowered by the four-bar linkage  28  to the operating position, with the bristles of the brush contacting the floor F ( FIG. 2 ) for scrubbing. The mechanical aspects of the raise and lower mechanism, which permits the brush to be set in the biased position indefinitely, are conventional. 
         [0028]    A Run Enable switch  33  and Brush Unload Enable switch  35  may be mounted to the frame of the machine. The functions of these switches will be described in connection with the schematic diagram,  FIG. 6 . The Unload Enable switch  35  is actuated by lever  29  and Run Enable switch  33  is actuated by a strike plate designated  31  in  FIGS. 1 and 2 . The strike plate  31  is mounted to an extension of the lever  29  which extends forwardly of the pivot  32  and which forms the lower link of the parallel linkage  28 . Briefly, the Run Enable switch allows the brush to be driven by the motor when the brush is lowered for use ( FIG. 2 ), and the Brush Unload Enable switch allows the brush to be driven for unload when the brush is in the raised position ( FIG. 1 ). 
         [0029]    Turning now to  FIG. 3 , the motor  22  (and associated gearing, if any) is conventional and need not be described in further detail. The motor  22  drives a shaft  34  which extends in a vertical direction for driving the brush  20 . The hub assembly  24  is connected to the drive shaft  34  and mounts the brush  20  as will be described in further detail. 
         [0030]    The brush  20  includes a brush plate  36 , the lower portion of which is provided with bristles  37 . The center of the brush plate  36  is increased in thickness, as at  38 , thus providing strength, and defining a receptacle generally designated  39  for receiving and releasably coupling to the hub assembly  24 , as will be described in more detail within. 
         [0031]    Briefly, the hub assembly  24  includes an upper hub member  42 , and a lower hub member (or “drive lug”)  43 . As will be described, the upper hub member  42  is placed respectively on the top of the central portion  38  of the brush  20 , and the lower hub member  43  of the hub assembly  24  is located beneath the upper hub member and attached to it by means of bolts  45  ( FIGS. 4 and 5 ). The hub assembly is fastened together by fasteners  45 , and when fastened together, they grip and hold the brush plate  36  as seen in  FIG. 3 . The brush assembly is secure to the shaft  34  of the motor by fastener  41 . As will be described, the upper hub member  24  applies the downward force on the brush  20 , and the lower hub member or drive lug  43  is received in the lower, central receptacle  39  of the brush plate  36 . The upper and lower hub members  42 ,  43  form the hub assembly  24 ; and they cooperate to provide an annular, circumferential retention groove or channel  48  for securing the brush  20  in the driving position of  FIG. 3 . 
         [0032]    Turning now to  FIGS. 4 and 5 , there are shown, respectively, an upper perspective view and a lower perspective view of the drive hub assembly  24  in cross section. When the two hub members  42 ,  43  are secured together, by the fastener  45 , they provide the retention groove or channel  48  for removably securing the brush. 
         [0033]    Turning then to the upper hub member  42 , it includes a central collar  51  which includes an axially extending key way  52  for coupling to the drive shaft  34  of the motor  22 . The drive shaft  34  is provided with a matching keyway providing a driving engagement for the drive hub assembly when the upper and lower members are secured together as described above. 
         [0034]    The upper hub member  42  also includes an outwardly extending circular flange  54  including a horizontally extending lower, generally flat lower surface  55  which extends horizontally when the hub assembly is connected to the drive shaft  34 . The lower horizontal surface  55  of the upper hub member  42  rests on the upper cylindrical surface of the raised central portion  38  of the brush plate  36 , and provides a means through which the upper hub member  42  exerts a downward force on the brush  20  when it is lowered to the operating position. The force may be provided by the weight of the motor  22  and the associated linkage assembly for positioning the drive motor. Additional force may be added by other means if necessary or desired. 
       Description of the Control Circuitry 
       [0035]    Turning now to  FIG. 6 , there is shown an electrical schematic of the control circuit for operating the scrubber as has been described above. Reference numeral  120  generally designates a battery which supplies power to the unit. The battery  120  may be comprised of one or more deep cycle batteries. A battery charger  121  (operating normally-closed contacts  125 ) is connected across the terminals of the battery, to be plugged into a wall outlet when it is desired to charge the battery. When the battery charger is in operation, a first Keyswitch  124  is prevented from operating the system because contacts  125  open. A double-pole connector has two contacts  123 ,  123  connected respectively in the battery supply leads for manually disconnecting the battery for safety or testing of the circuit. Contacts  2  of first Keyswitch  124  (which is shown in electrical schematic form for switch  18  in  FIG. 1 , battery charger contact  125 , and circuit breaker  128  are connected between junctions  157  and  148 . 
         [0036]    A brush relay designated  122  is connected in series with the normally-closed (i.e. when the brush is in the lowered position) Run Enable switch  33  and the normally-open Operator Run switch  17  A (shown in  FIG. 6  in electrical schematic form). These three components are connected in a series circuit. One terminal of the Operator Run switch  17  A is connected to a junction  152 . Two normally-open contacts  131 ,  131  of main relay  130  are connected respectively in the positive and negative battery leads. Keyswitch  124 , which enables the operator to turn the system “on” or “off” and provides security, is connected as shown. First Keyswitch  124  is a spring biased, multiple contact switch. Briefly, switch  162  of first Keyswitch  124  is connected between junction  148  and the battery supply. Switch  161  is connected in series with normally-closed Unload Enable switch  35 ; switch  160  is connected to junction  148 , and switch  155  (which operated with switch  160 ) is connected to junction  152 . Contacts  125  of an internal relay of battery charger  121  are connected in series with a circuit breaker  128  and first Keyswitch  124 . A main relay  130  is connected between junction  148  and battery negative. First Keyswitch  124  has three positions: Off (designated 0); On (designated 2); and Brush Unload (designated I in the drawing). When the contact (which is actuated by turning the key) moves to the numbered position, the similarly numbered contacts are actuated, as will be further described. In the Brush Unload position, first Keyswitch  124  is spring-biased to the off position and returns if released by the operator. 
         [0037]    The upper set of normally-open contacts  131  of the main relay  130  couple power, when closed, to a junction  156 . A vacuum switch  145  is connected between junction  148  and a vacuum relay  146 , thus energizing a vacuum motor  132  when switch  145  is closed by the operator and junction  148  is energized. 
         [0038]    In series with the circuit containing the brush motor  135  are normally-open contacts  136  actuated by a brush relay  122 . A circuit breaker  137  is connected in series with the normally-open contacts  136 . For reasons which will become clear, the terminals of brush motor  135  are shown as terminals  138  and  139  (which is connected to the battery negative supply line  153  when the system is in operation). 
         [0039]    Normally-open contacts  140  (actuated by the vacuum relay  146 ) are connected in circuit with a circuit breaker  141  and a vacuum motor  132  for actuating the vacuum recovery system. 
         [0040]    A vacuum switch  145 , normally closed, is connected in series with the vacuum relay  146 , this circuit being connected to the junction  148 , as seen. A battery gauge  149  is also connected to the junction  148 . 
         [0041]    Turning to the right side of  FIG. 6 , the previously described Operator Run switch  17 A, (bail-operated and having normally-open contacts) is connected in series with the normally-closed contacts of the Run Enable switch  33 . The Run Enable switch  33  is actuated to the closed position by the strike plate  31  being in the lowered position, as seen in  FIG. 2 . When the Run Enable switch  33  is closed (the strike plate  31  being lowered with the brush by action of the operator), the operator may then operate the machine by actuating (via the bail  17 ) the Operator Run switch  17 A. Junction  152  is a common junction for switch  155  of the first Keyswitch  124 , the circuit comprising the Run Enable switch  33  and the Operator Run switch  17 A just described; the brush relay  122 ; and a series circuit comprising a water solenoid switch  129  and solenoid  126  for opening a valve to the water supply when switch  129  is closed by the operator&#39;s release of foot pedal  30 . 
         [0042]    The first Keyswitch  124  includes a set of normally-open contacts  155  which are connected to the junction  152 . Normally-closed contacts  161  of the first Keyswitch  124  are connected in circuit with the normally-open Unload Enable switch  35  (shown in  FIG. 6  in the closed position because  FIG. 6  represents the system in the Transport Mode) which is connected to brush motor terminal  138 , and normally-closed contacts  159  of the brush relay  122 , which are connected to brush motor terminal  139 . 
       Operation of the Circuitry 
     Normal Running Operation 
       [0043]    The electrical schematic of  FIG. 6  is shown in the transport mode. Thus, for example, the normally closed Run Enable switch  33  is shown as open in  FIG. 6  and normally open Unload Enable switch  35  is shown as closed. Assuming the battery  120  is connected (switches  123  closed), when a key is inserted in first Keyswitch  124  and turned by the operator to position “2”, switch  162  closes, and the battery  120  is connected through the circuit breaker  128 , normally-closed contacts  125  of battery charger  121  (since battery charger  121  is not in operation) and contacts  162  of the Keyswitch  124  to the junction  148 . This operates the battery gauge  149  for operator observation, and it also actuates the main relay  130 . 
         [0044]    When the main relay  130  is energized, contacts  131 ,  131  close, supplying power to modes  153  and  156 . If the vacuum switch  145  is closed (manually), the vacuum relay  146  is energized, thereby closing the contacts  140  and energizing the vacuum motor (i.e., pump)  132 . 
         [0045]    Assuming that the brush is in the lowered or operating position, the Run Enable switch  33  is closed. This then couples power from junction  148  through the Run Enable switch  33  and the Operator Run switch  17 A (when bail or actuator  17  is moved by the operator) to the junction  152 . This actuates the brush relay  122  which, in turn, closes contacts  136  to energize the brush motor  135  to drive the brush  20 . At the same time, the water solenoid  125  (optional) may be energized to supply water to the brush  20  because switch  129  is normally closed. 
         [0046]    Operation continues until the operator releases the bail handle  17  which then opens the Operator Run switch  17 A, thereby opening the contacts of switch  17 A in  FIG. 6  to de-energize the brush relay  122  and thereby, de-energize the brush motor  135 . 
       Transport and Brush Unload 
       [0047]    For transport, storage or brush unload (to clean, store or charge, for example), the foot pedal  30  is depressed by the operator. This raises the brush  20  to the raised position shown in  FIG. 2 , and the control circuit is as shown in  FIG. 6 . To unload the brush, the operator turns the first Keyswitch  124  to position “1”, which is spring biased to return to the “OFF” or “0” position when the key is released. 
         [0048]    When the key is in position “1”, contacts  160  and  155  are closed. Contacts  155  cause the brush relay  122  to be energized via junction  152 . This closes contacts  136  to energize the brush motor  135  which drives the brush in rotation (in the raised position). When the brush reaches normal speed (or even less), the operator releases the key, and the Keyswitch reverts under spring bias to position “0”. In this position, contacts  155  and  160  open and contacts  161  close. This action shorts out the terminals  138 ,  139  of brush motor  135  via the circuit comprising: terminal  138 , Unload Enable switch  35  (actuated to the closed position by virtue of manually raising the brush); closed contacts  161  (switch position “0”); and brush relay contacts  159  to motor terminal  139 . 
         [0049]    If it is desired to remove the brush the operator depresses the foot pedal  30 , elevating the brush to the raised position which, in turn, closes the Unload Enable switch  35 . This opens contacts  33  and closes contacts  35  of the Unload Enable switch, thereby permitting a brush removal because the brush is raised. 
         [0050]    When the circuit is in this condition, if the operator rotates the Keyswitch  124  to the “Brush Unload” position, the contacts  155  and  160  close. This causes the main relay  130  and brush relay  122  to be momentarily energized, thereby enabling the brush motor  135  to be energized through contacts  136  (contacts  161  being open). When the operator then releases the Keyswitch  124 , it returns to position “0” under spring bias. Contacts  155  and  160  open, de-energizing the brush relay  122  and main relay  130  via junction  148 , thereby opening contacts  136 . At the same time, contacts  161  of the Keyswitch  124  are closed, as is the Unload Enable switch  35  by the operator, thereby placing a load to decelerate motor  135  and bringing the motor to a quick stop due to the load. This permits the brush to override the drive lug and be disengaged, and to fall freely from the brush drive assembly, or to be removed manually. 
         [0051]    While various functions of the present invention are described as being carried out by control circuitry illustrated in  FIG. 6 , various of these functions could be carried out by proper programming of control circuitry located in controller  204  by one skilled in the art. 
         [0052]    Referring to  FIG. 8 , there is shown a simplified side elevation view of a floor cleaning machine  10  in accordance with the present invention. In addition to the components described above, the inventive floor cleaning machine  10  further includes an ozone generator controller  200  and an ozone cell  206  capable of generating ozone in liquid form. Floor cleaning machine  10  further includes a clean water reservoir  208  which provides clean water to a cleaning solution pump  202 . Cleaning solution pump  202  is connected to and provides cleaning solution to the ozone cell  206  via a flow sensor  204 . Ozone cell  206  is connected to rotating brush  20  by means of a conduit  210  for providing a mixture of the cleaning solution and ozone liquid to the brush for cleaning a floor surface. Ozone generator controller  200  is coupled to ozone cell  206  as well as to flow sensor  204 . Ozone generator controller  200  provides input power to and control for the ozone cell  206 . Cleaning solution pump  202  receives clean water from reservoir  208  and pumps the clean water to the flow sensor  204 . Flow sensor  204  is in communication with the ozone generator controller  200  and provides cleaning solution flow information to the ozone generator controller. In response to inputs from flow sensor  204 , ozone generator controller  200  initiates operation of the ozone cell  206  upon the detection of cleaning fluid flow by flow sensor and maintains operation of the ozone cell so long as there is a detectable flow of the cleaning solution. When the cleaning solution pump  202  is turned off, flow sensor  204  provides an appropriate signal to ozone generator controller  200 , whereupon the ozone generator controller provides an output signal to the ozone cell  206  terminating operation of the ozone cell and the flow of ozone in the system. It should be noted that in some systems cleaning solution may flow under the influence of gravity and the cleaning solution pump  202  may not be needed in such systems. In addition, flow sensor  204  may also not be needed in some mobile cleaning machines as there are other available conventional approaches well known to those skilled in the relevant art to detect the flow of a first solution and exercise control over the flow of a second solution. The ozone cell  206  may be installed at various locations in the water circulating system such as immediately adjacent the brush  20  as shown in dotted line form in  FIG. 8 . 
         [0053]    Referring to  FIG. 9 , there is shown a simplified sectional view of an ozone cell  214  for use in the present invention. Ozone cell  214  includes a housing  216  containing an anode  218 , a cathode  222  and an ion permeable membrane  220 . Anode is preferably comprised of PbO 2 , Pt or boron-doped diamond. Cathode is preferably comprised of Pt or diamond. A DC voltage is applied across anode  218  and cathode  222  at a value on the order of 1.6 VDC. Water is directed into two inlets within housing  216  so as to create one flow channel over an outer surface of anode  218  and a second flow channel across the outer surface of cathode  222 . The combination of water and ozone exits housing  216  via a first outlet  224 , while water and hydrogen is discharged from a second outlet  226  of the housing. One example of an ozone cell which could be used in the present invention is available from Electrolytic Ozone, Inc., which is currently located in the Boston, Mass. area. 
         [0054]    While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the claims when viewed in their proper perspective based on the prior art.