TECHNICAL FIELD
The disclosure herein relates generally to walk-in refrigerators, including walk-in freezers and coolers.
BACKGROUND
Historically, walk-in coolers and freezers are typically designed and used primarily in the commercial food service industry. While demand for walk-in refrigerators for residential use has recently risen, simply placing a commercial system into a residential environment raises numerous issues related, for example, to noise, user comfort and temperature management. These issues, among others, are addressed by implementations of the systems disclosed herein.
SUMMARY
One or more deficiencies of the prior art are solved by way of embodiments of a walk-in refrigeration system, and components, subassemblies and methods thereof, in accordance with the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description of the preferred embodiments and upon reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic perspective view illustrating one example walk-in refrigeration system in accordance with the present disclosure;
FIG. 2 is a further diagrammatic perspective view of the example walk-in refrigeration system of FIG. 1;
FIG. 3 is diagrammatic side view of the example walk-in refrigeration system of FIG. 1;
FIG. 4 is diagrammatic front view of the example walk-in refrigeration system of FIG. 1;
FIG. 5 is diagrammatic cross-sectional view taken along lines 5-5 in FIG. 3;
FIG. 6 is magnified view of detail 6 in FIG. 5;
FIG. 7 is diagrammatic cross-sectional view taken along lines 7-7 in FIG. 4;
FIG. 8 is magnified view of a portion of FIG. 7;
FIG. 9 is magnified view of detail 9 in FIG. 8;
FIG. 10 is diagrammatic perspective view of the walk-in refrigeration system of FIG. 1 subjected to the cross-sectional cut applied in FIG. 7;
FIG. 11 is magnified view of detail 11 in FIG. 10, illustrating details of an example air curtain plenum and associate features;
FIG. 12 is diagrammatic partial cross-sectional view taken along lines 12-12 in FIG. 3, illustrating example air flow and temperature control of the system;
FIG. 13 is magnified view of detail 13 in FIG. 12;
FIG. 14 is diagrammatic perspective view of the walk-in refrigeration system of FIG. 1 subjected to the cross-sectional cut along lines 14-14 in FIG. 3;
FIG. 15 is magnified view of detail 15 in FIG. 14, illustrating an example interface panel with vent segment, and associated components and features;
FIG. 16 is magnified view of detail 16 in FIG. 14, further illustrating an example interface panel with vent segment, and associated components and features;
FIG. 17 is a diagrammatic partial perspective view illustrating an initial unlocking movement of an example interface panel out of its secured engagement with associated standoff brackets, thereby allowing the interface panel to be removed from the associated interface wall;
FIG. 18 is a diagrammatic partial perspective view similar to that of FIG. 17, but wherein the interface panel is shown having been removed from the associated interface wall;
FIG. 19 is a partial perspective view of an example standoff bracket;
FIG. 20 is a partial front view of the example standoff bracket of FIG. 19;
FIG. 21 is a diagrammatic plan view of an example interface panel blank cut out of sheet metal stock;
FIG. 22 is a diagrammatic perspective view of an example interface panel formed from the interface panel blank of FIG. 21 after undergoing the requisite bending operations;
FIG. 23 is a diagrammatic partial perspective view of an example interface panel with metering element in disassembled configuration;
FIG. 24 is a diagrammatic partial perspective view similar to that of FIG. 23, but wherein the example interface panel with metering element is shown in an assembled configuration;
FIG. 25 is a diagrammatic partial perspective view of the walk-in refrigeration system, showing details of an interface panel with metering element, and associated components and features;
FIG. 26 is a diagrammatic perspective view of the example walk-in refrigeration system of FIG. 1, but with the insulation walls and associated outer panels shown removed from the remainder of the system;
FIG. 27 is a further diagrammatic perspective view of the example walk-in refrigeration system of FIG. 1, but without the insulation walls and associated outer panels;
FIG. 28 is a diagrammatic partial perspective view of the example walk-in refrigeration system of FIG. 1, but without the roof insulation wall so as to reveal details of the ceiling panel assembly and supply plenum;
FIG. 29 is a diagrammatic top view of the example walk-in refrigeration system of FIG. 1, but without the roof insulation wall so as to reveal details of the ceiling panel assembly and supply plenum;
FIG. 30 is a diagrammatic perspective view of an example ceiling panel assembly;
FIG. 31 is a diagrammatic partial perspective view of an example intermediate panel;
FIG. 32 is a diagrammatic partial perspective view of an example intermediate shelf bracket;
FIG. 33 is a diagrammatic perspective view of an example first inboard wall assembly, shown in a disassembled configuration;
FIG. 34 is a diagrammatic perspective view of the example first inboard wall assembly of FIG. 33, but shown in an assembled configuration;
FIG. 35 is a further diagrammatic perspective view of the example first inboard wall assembly of FIG. 34;
FIG. 36 is a diagrammatic perspective view of an example second inboard wall assembly, shown in an assembled configuration;
FIG. 37 is a further diagrammatic perspective view of the example second inboard wall assembly of FIG. 36;
FIG. 38 is a diagrammatic perspective view of an example third inboard wall assembly, shown in an assembled configuration;
FIG. 39 is a further diagrammatic perspective view of the example third inboard wall assembly of FIG. 38;
FIG. 40 is diagrammatic cross-sectional view taken along lines 5-5 in FIG. 3, but wherein the walk-in refrigeration system further includes a third inboard wall assembly disposed at the rear of the insulated compartment; and
FIG. 41 is diagrammatic cross-sectional view of a further example implementation of a walk-in refrigeration system, illustrating example airflow and temperature control aspects of the system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, like reference numerals designate identical or corresponding features throughout the several views.
With reference to the several drawings, example implementations of a walk-in refrigeration system are shown generally at 100. Referring to FIGS. 1, 5 and 40, the system 100 may comprise a main enclosure 102, an insulted compartment 128, a main door 132, and one or more inboard wall assemblies (such as shown at 170, 172, 173).
Referring to FIGS. 5, 7 and 26, the main enclosure 102 may have a first lateral insulation wall 104, a second lateral insulation wall 106 disposed oppositely thereof, a rear insulation wall 108, a front insulation wall 110, and a roof insulation wall 112. The first lateral insulation wall 104 may comprise one or more first lateral insulation panels 116. The second lateral insulation wall may comprise one or more a second lateral insulation panels 118. The rear insulation wall 108 may comprise one or more rear insulation panels 120. The front insulation wall 110 may comprise one or more front insulation panels 122. The room insulation wall 112 may comprise one or more roof insulation panels 124. The insulation panels may comprise, for example, a conventional thermal insulation material.
Referring to FIGS. 5 and 7, the insulated compartment 128 may be defined within the main enclosure 102. The main enclosure 102 may be configured to thermally insulate the insulated compartment 128 from an ambient environment 130 external to the main enclosure 10. Referring to FIGS. 5 and 41, the insulated compartment 128 may include a first shelf refrigeration zone 144, a second shelf refrigeration zone 146, a walk-in zone 148, a first wall plenum 150, a second wall plenum 152, and a supply plenum 154. One or more lateral shelves 138 may be supportedly mounted within the first and second shelf refrigeration zones. Referring o FIG. 15, the shelves 138 may preferably include shelf base apertures 168.
Referring to FIG. 5, the main door 132 may be disposed between the walk-in zone 148 and the ambient environment 130, and may be configured to be opened (e.g., by way of hinged or slidable movement of the main door 132 with respect to the front insulation wall 110) to enable a person (i.e., the person's complete body) to pass entirely between the ambient environment 130 and the walk-in zone 148. The main door 132 may be mounted in the front insulation wall, and may include a main door handle 162 The front door 132 may have a transparent portion which allows the insulated compartment 128 to be viewable from a viewing position outside the main door 132 while the main door 132 is closed. For example, the main door 132 may include an inner window panel 156 and outer window panel 158, with spacing (e.g., gas compartment) therebetween to facilitate the insulative characteristics of the main door 132. This spacing may sealingly house a gas such as, for example, air or Argon. Referring to FIGS. 5 and 7, the system 100 may include a floor portion 114. The floor portion 114 may include a floor ramp portion 164 disposed between the main door 132 and the walk-in zone 148. A floor trough 160 may be disposed within the floor portion 114, for example toward the bottom of the floor ramp portion 164.
Referring to FIGS. 7 and 12, the supply plenum 154 may be disposed between the roof insulation wall 112 and a ceiling panel 246, and may be configured to retain an evaporator 226 of a heat exchange subsystem 224 therein. The heat exchange subsystem 224 may include the evaporator 226, an evaporator fan 228, a condenser 230, a condenser fan 232, a compressor 234 and an expansion valve 236. The evaporator fan 228 may include a variable-speed motor. A remote portion 238 of the heat exchange subsystem 224 may be defined by at least the condenser 230, the condenser fan 232 and the compressor 234. The remote portion 238 may be placed at a selected distance from the main enclosure 102. Remoting the refrigeration reduces the internal BTU/H heat load of a house within which the system 100 operates.
Referring to FIGS. 5 and 41, the first wall plenum 150 may be defined between the first lateral insulation wall 104 and a first interface wall 248. Similarly, the second wall plenum 152 may be defined between the second lateral insulation wall 106 and a second interface wall 250.
Referring to FIGS. 12 and 41, the first wall plenum 150 may be in airflow communication between the supply plenum 154 and the first shelf refrigeration zone 144. Similarly, the second wall plenum 152 may be in airflow communication between the supply plenum 154 and the second shelf refrigeration zone 146. Referring to FIGS. 5 and 41, the walk-in zone 148 may be disposed between the first shelf refrigeration zone 144 and the second shelf refrigeration zone 146. Example system 100 airflow is illustrated in FIG. 41, which includes wall plenum airflow 268, discharge airflow 270 and return airflow 272.
Referring to FIGS. 35 and 41, the first interface wall 248 may include a plurality of flow discharge ports 176 configured to direct airflow from the first wall plenum 150 to the first shelf refrigeration zone 144. Similarly, referring to FIGS. 35 and 41, the second interface wall 250 may include a plurality of flow discharge ports 176 configured to direct airflow from the second wall plenum 152 to the second shelf refrigeration zone 146. Depending upon the particular implementation of the system 100, the flow discharge ports may be of various shapes and sizes, such as circular or elongated.
Referring to FIGS. 12 and 41, preferred implementations of the walk-in refrigeration system 100 comprise one or more air movement devices, such as wall plenum blower fans 184, to move air from the supply plenum 154 to the respective wall plenums. More example, one or more wall plenum blower fans 184 may be mounted in airflow communication between the supply plenum 154 and the first wall plenum 150 (example wall plenum airflow being shown at 268). Similarly, one or more wall plenum blower fans 184 may be mounted in airflow communication between the supply plenum 154 and the second wall plenum 152. The plenum blower fans 184 may include a blower shroud 186 to assist in directing air from the supply plenum 154 to the respective wall plenum.
Referring to FIGS. 1 and 5, certain implementations of the walk-in refrigeration system 100 may comprise an auxiliary access door 142 in communication between the ambient environment 130 and the first shelf refrigeration zone 144. Such an access door would allow a user to selectively reach into the first shelf refrigeration zone 144 without having to entirely enter the walk-in refrigeration system 100 through the main door 132.
Referring to FIGS. 33 and 35, the first interface wall 248 may be comprised of an array of first interface panels 134. Similarly, referring to FIG. 36, the second interface wall 250 may be comprised of an array of second interface panels 136.
Referring to FIGS. 17 and 18, the first interface panels 134 may be individually removable and replaceable with respect to the first interface wall 248. Similarly, the second interface panels 136 may be individually removable and replaceable with respect to the second interface wall 250.
Referring to FIGS. 15, 16 and 41, the first interface panels 134 and second interface panels 136 may each include a vent segment 174. The vent segments 174 of the first interface panels 134 may define flow discharge ports 176 in the first interface wall 248 configured to direct airflow from the first wall plenum 150 to the first shelf refrigeration zone 144. Similarly, the vent segments 174 of the second interface panels 136 may define flow discharge ports 176 in the second interface wall 250 configured to direct airflow from the second wall plenum 152 to the second shelf refrigeration zone 146.
Referring to FIGS. 5 and 6, the first interface wall 248 may be mounted at a distance inward of the first lateral insulation wall 104 by way of one or more standoff brackets 166, thereby forming the first wall plenum 150. Similarly, the second interface wall 250 may be is mounted at a distance inward of the second lateral insulation wall 106 by way of one or more standoff brackets 166, thereby forming the second wall plenum 152. The standoff brackets 166 may be configured to be affixed to the respective insulation wall by way of, for example, self-tapping screws, adhesives, a combination thereof or the like. For example, with reference to FIG. 19, the standoff bracket 166 may include one or more wall mount flanges 198, which in turn may include several wall mounting apertures 200 for receiving self-tapping screws therethrough. Referring to FIGS. 33-39, it is envisioned that this standoff bracket configuration could facilitate retrofitting of existing walk-in refrigerators, by enabling inboard wall assemblies such as those shown at 170, 172 and 173 to be rapidly sized and affixed to respective interior walls of the existing refrigerator.
Referring to FIGS. 17-20, the standoff brackets 166 may be elongated along standoff bracket axis 202, and may include a multiplicity of panel mount apertures 194. Correspondingly, the first interface panels 134 and second interface panels 136 may each include panel mounting portions 192 configured to mountingly engage the panel mount apertures 194. For example, as illustrated in FIGS. 17-20, the panel mount apertures 194 may take the form of elongated vertical slots, and the panel mounting portions 192 may be in the form of planar hooks configured to be received by the slots 194 and thereafter moved into secured engagement with the standoff bracket 166.
Referring to FIGS. 19 and 20, the standoff brackets 166 may include a multiplicity of shelf mount apertures 196. Correspondingly, the system 100 may include shelf brackets 182 (see, for example, FIG. 32) having shelf bracket mounting portions 190 configured to mountingly engage the shelf mount aperture 196. Referring to FIGS. 15 and 41, the system 100 may comprise a plurality of lateral shelves 138 supportedly mounted to respective shelf brackets 182 within the first refrigeration zone 144 and second shelf refrigeration zone 146. Referring to FIG. 20, in particular implementations of the system 100, on each standoff bracket 166, the shelf mount apertures 196 may be disposed between the panel mount apertures 194. Moreover, referring to FIG. 19, the standoff brackets 166 may include air passthrough ports 262. In such case, on each standoff bracket 166, the panel mount apertures 194 may be disposed between the air passthrough ports 262.
Referring to FIGS. 12 and 41, in preferred implementation of the system 100, the ceiling panel 246 may include a ceiling vent 126 in airflow communication between the walk-in zone 148 and the evaporator 226. Most preferably, the ceiling vent 126 is disposed directly above (e.g., in lateral alignment with) the walk-in zone 148. Referring to FIGS. 28-30, an example of a ceiling panel assembly 244 is shown.
Referring to FIGS. 8-11, particular implementations of the walk-in refrigeration system 100 may further comprise one or more wall plenum blower fans 184 mounted in airflow communication between the supply plenum 154 and an air curtain plenum 252 above the main door 132. An air curtain discharge vent 254 may be disposed between the air curtain plenum 252 and the area directly inside the main door 132, to generate an air curtain 188 across the main door 132. The plenum blower fans 184 corresponding to the air curtain plenum 252 may be configured to turn on only when the main door 132 is opened. Referring to FIG. 11, certain implementations of the system 100 may further comprise a light reflector element 256 disposed within the air curtain plenum 252. The light reflector element 256 may be configured to reflect light from a light source horizontally (e.g., parallel to light direction 258) toward the walk-in zone 148. The light source may be, for example, an LED fixture or the like. Referring to FIG. 9, the LED fixture may be mounted in, for example, an LED fixture mount 260.
Referring to FIGS. 38 and 40, in certain implementations of the walk-in refrigeration system 100, the insulated compartment 128 may include a rear shelf refrigeration zone 147 and a rear wall plenum 153. The rear wall plenum 153 may be defined between the rear insulation wall 108 and a rear interface wall 251. The rear wall plenum 153 may be in airflow communication between the supply plenum 154 and the rear shelf refrigeration zone 147. The rear shelf refrigeration zone 147 may be disposed between the rear interface wall 251 and the walk-in zone 148. One or more rear shelves 140 may be supportedly mounted within the rear shelf refrigeration zone 147. The rear interface wall may be defined by an array of third interface panels 137.
Referring to FIGS. 31 and 33, particular implementations of a walk-in refrigeration system 100 may further comprise one or more intermediate panels 204. The intermediate panels 204 may have one or more light fixture mounts 264 and one or more light emission apertures 266. The intermediate panels 204 may also include a plurality of panel mounting portions 192 configured to mountingly engage the panel mount apertures 194 in the standoff brackets.
Referring to FIGS. 15 and 16, in particular implementations of the walk-in refrigeration system 100 in which the interface panels include vent segments 174, the vent segment 174 may each include one or more capture inlet ports 178 and a flow deflection portion 180 disposed in airflow communication between the one or more capture inlet ports 178 and the flow discharge port 176 of the vent segment 178. In such case, the flow deflection portion 180 may be configured to change the direction of airflow entering the one or more capture inlet ports 178 as it flows toward the flow discharge port 176. The flow deflection portion 180 may present a ramp angle of, for example, between 30-60 degrees, and preferably 45 degrees, to the incoming wall plenum airflow. As illustrated in FIGS. 21 and 22, the interface panels may be formed from an interface panel blank 242, which may be comprised of a sheet metal. The interface panel blank 242 may be cut out, then bent as indicated to form the interface panel shown in FIG. 22.
Moreover, referring to FIGS. 23 and 24, one or more of the interface panels (for example, interface panel 136) may include an actuatable metering element 208. Actuation of the metering element 208 (e.g., in direction 240) may be configured to selectably restrict the airflow through the one or more capture inlet ports 178. Referring to FIG. 25, each metering element 208 may include a meter actuation tab 212 configured to extend through a respective one of the one or more capture inlet ports 178. The selectable restriction of the airflow through the capture inlet ports 178 may be by way of adjustable alignment offset between metering apertures 210 in the metering element 208, and respective capture inlet ports 178. A capture face 206 on the upper edge of the vent segment 174 may provide a guiding surface for slidable engagement between the metering element 208 and the vent segment 174. As illustrated in FIGS. 23 and 24, the metering element 208 may be slidably attached to the vent segment 174 by way of a metering element fastener 214 (e.g., a threaded bolt) extending through a fastener aperture 222 in the vent segment 174, through a transportation guide slot 220 in the metering element 208, and secured by a fastener detent 216 (e.g., a threaded nut) on the other side. A washer 218 may also be implemented as shown.
The particular removable interface panels shown at 134, 136 and 137 provide aesthetic advantages, for example by hiding the flow discharge ports 176 from a user standing within the walk-in zone 148. Also, the configuration of these interface panels direct air to and across product placed on adjacent shelves to optimize product cooling. These interface panels can be removed by hand for easy cleaning, and the flow discharge ports 176 are hidden (laterally and from above) to prevent food or liquids from entering the respective wall plenum in the event of spillage.
The system 100 implementations shown in the several figures provide lock-in shelving to prevent accidental dislodging of the shelves from the respective walls. Certain aspects of the system 100, including plenum configuration and fan placements, help minimize the noise experienced by a user standing within the walk-in zone. Conventional commercial walk-in boxes tend to have uneven temperatures due to poor air circulation throughout the entire refrigeration compartment. The supply plenum 154 of the disclosed system 100 serves as a cooling reservoir feeding multiple wall plenums. The blower fans pull from the supply plenum to enable the wall plenums to efficiently and quietly circulate the cooled air throughout the environment in which the product is stored. The distributed airflow configuration of the system 100 also increases the comfort of the user within the walk-in zone, in part by preventing evaporator fans from blowing large, concentrated volumes of cold air into the walk-in space.
In certain preferred embodiments of the system 100, the inboard wall assemblies are made up of onboard air panels (otherwise referred to herein as interface panels) held, for example, 1.5 inches off the insulated wall which creates an air plenum. A series of hidden sensor controlled, silent secondary squirrel cage fans, which are mounted where side walls meet ceiling. Secondary fans push condensed refrigerated air down the backside of panels. Plenums build pressure forcing the air out the elongated vents that are across each air wall panel. Air then pulled back up to the return in the ceiling and then repeats 360 vortex cycle. Onboard air panels can easily be removed in seconds without the use of tools, for cleaning and/or to change out to a different color for aesthetic transformation. Each airwall vent segment may have an independent adjustable damper (metering element) to infinitely control the rate of speed air can flow, going full discharge when completely open, to zero when completely closed. This will allow moisture control preventing dryness of produce and or other unpackaged foods. The inboard wall assemblies work as an intervening refrigerated air supply, discharging cold air from ceiling to floor through concealed slots that blow air down to a 450 angle which deflects air across shelves. This allows for optimal cold air distribution throughout every square inch of the walk-in cooler. This design slows down the velocity of air making for a comfortable and non-obtrusive experience when inside, whereas typical walk-in refrigerators have a blower coil evaporator with high powered fan mounted to the ceiling, which produces a powerful blast of air with little or no control of its coverage. And since cold falls, this can leave inconsistent temperatures throughout the interior. Bright interior LED lighting with white translucent polycarbonate lens diffusers over the light emission apertures allows for optimal illumination throughout. RGB app-controlled multi-colored adjustable color LED light strips may be disposed behind same polycarbonate lenses. The inboard wall assemblies may substantially reduce the dBA noise level compared to a standard walk-in cooler. A pressure equalization system may be provided for safety, to eliminate negative air pressure vacuum, so the main door opens freely with no restriction.
The following listing matches certain terminology used within this disclosure with corresponding reference numbers used in the non-limiting embodiments illustrated in the several figures.
- 100 walk-in refrigeration system
- 102 main enclosure
- 104 first lateral insulation wall
- 106 second lateral insulation wall
- 108 rear insulation wall
- 110 front insulation wall
- 112 roof insulation wall
- 114 floor portion
- 116 first lateral insulation panel
- 118 second lateral insulation panel
- 120 rear insulation panel
- 122 front insulation panel
- 124 roof insulation panel
- 126 ceiling vent (e.g., disposed between walk-in zone and supply plenum)
- 128 insulated compartment
- 130 ambient environment (external to main housing)
- 132 main door
- 134 first interface panel
- 136 second interface panel
- 137 third interface panel
- 138 lateral shelf
- 140 rear shelf
- 142 auxiliary access door
- 144 first shelf refrigeration zone
- 146 second shelf refrigeration zone
- 147 rear shelf refrigeration zone
- 148 walk-in zone
- 150 first wall plenum
- 152 second wall plenum
- 153 rear wall plenum
- 154 supply plenum
- 156 inner window panel
- 158 outer window panel
- 160 floor trough
- 162 main door handle
- 164 floor ramp portion
- 166 standoff bracket
- 168 shelf base aperture
- 170 first inboard wall assembly
- 172 second inboard wall assembly
- 173 third inboard wall assembly
- 174 vent segment (e.g., of interface panels)
- 176 flow discharge port (e.g. defined within or between interface panels)
- 178 capture inlet port
- 180 flow deflection portion (e.g., deflection ramp)
- 182 shelf bracket
- 184 wall plenum blower fan
- 186 blower shroud
- 188 door air curtain
- 190 shelf bracket mounting portions (e.g., hook members)
- 192 panel mounting portions (e.g., hook members)
- 194 panel mount apertures (e.g., elongated slots)
- 196 shelf mount apertures (e.g., elongated slots)
- 198 wall mount flange
- 200 wall mount aperture (e.g., for receiving mounting screws)
- 202 standoff bracket axis
- 204 intermediate panel
- 206 capture face
- 208 metering element
- 210 metering aperture
- 212 meter actuation tab
- 214 metering element fastener (e.g., bolt)
- 216 fastener detent (e.g., nut)
- 218 washer
- 220 transport guide slot
- 222 fastener aperture
- 224 heat exchange subsystem
- 226 evaporator
- 228 evaporator fan
- 230 condenser
- 232 condenser fan
- 234 compressor
- 236 expansion valve
- 238 remote portion (of heat exchange subsystem)
- 240 meter actuation direction
- 242 interface panel blank
- 244 ceiling panel assembly
- 246 ceiling panel
- 248 first interface wall
- 250 second interface wall
- 251 third interface wall
- 252 air curtain plenum
- 254 air curtain discharge vent
- 256 light reflector element
- 258 light direction (of emitted or reflected light)
- 260 light fixture mount (e.g., for waterproof LED fixture)
- 262 air passthrough port
- 264 light fixture mount
- 266 light emission aperture
- 268 wall plenum airflow
- 270 discharge airflow
- 272 return airflow
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.