DISPLAY CASE INCLUDING SLIDING DOOR SYSTEM

Abstract

A refrigerated display unit comprising a display case that defines and separates a product display area from an environment; the display case having a frame that defines one or more openings to the product display area; an upper rail connected to the display case and extending at least partially along the frame; a first door and a second door movably connected to the upper rail; the first door being configured to move between a closed position adjacent to the frame and a first open position where the first door is positioned over the second door; the second door being configured to move between a closed position adjacent to the frame and a second open position where the second door is positioned over the first door.

Description

DISPLAY CASE INCLUDING SLIDING DOOR SYSTEM BACKGROUND OF THE INVENTION The present invention relates to refrigerated display cases, and more specifically to door assemblies for refrigerated display cases. Existing refrigerated display cases typically include a cabinet that defines a product display area to hold and / or showcase products that will be visible and accessible through an opening in the front of the cabinet. Some refrigerated display cases, such as low-temperature display cases used for frozen products, include doors that enclose the product display area. The doors typically include one or more glass panels that allow the consumer to view the products stored inside the cabinet. The doors are supported by a frame that includes a top, a bottom, and a pair of side rails. If the display case includes more than one door, mullions may be placed between the doors, extending from the top to the bottom. The doors on existing display cases are pivotally connected to the frame, opening outward toward the customer.These doors swing out of the display case cover and take up additional space on the aisle floor, requiring relatively wide aisles to accommodate the displays on opposite sides of the aisle. BRIEF DESCRIPTION OF THE INVENTION The invention provides a sliding door assembly for display cases that have glass enclosures to maintain products at low temperatures (e.g., -23.33°C (-10° Fahrenheit)) and to minimize the door's footprint when moved between an open and closed position. Unlike pivot or swing doors, the sliding door typically remains inside the glass enclosure. With a sliding door design, aisles can be made narrower without sacrificing accessibility. Additionally, the overall footprint of the installation can be reduced, or the extra floor space gained by using the sliding door can be used to display an additional product. The difficulty in implementing a door that moves laterally and outward in a refrigerated display case lies in achieving an airtight seal between the door and the display case. The sliding door of the present invention solves this problem by incorporating a door with a path and approach angle relative to the display case that combine lateral movement with outward or inward movement of the door. In this way, the sliding door can be opened and closed in a direction that is substantially normal or perpendicular to the display case or door frame. This approach angle also facilitates the use of a seal (e.g., a magnetic seal) between the door and the frame. In one aspect, the invention provides a roll-up sliding door for a refrigerated display case. For example, the door is configured to move around more than one axis (e.g., to slide, roll, roll laterally relative to the display case, and to move outward and inward relative to the display case on a rail system). In some aspects, a user can pick up the door and move the door along a rail system, or the movement can be initiated and controlled by a controller that is coupled to a motor that in turn is coupled to the door (e.g., via one or more switches or controls). In one aspect, the door may include or be connected to an automated storage and retrieval system (ASRS) via integration controls between the display and the ASRS. For example, the door's rail system has an electromechanical switching mechanism that can select one of at least two paths for the door, depending on the status of each door in a pair of two doors (e.g., one or both doors open). In one aspect, the rail system includes a four-bar linkage system with a mechanical activation device to select the rail or path to follow. In another aspect, the system can be controlled with a solenoid actuator to move the switch between alternate paths or rails. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a front perspective view of an exemplary refrigerated display case including a showcase frame and door rail assemblies. Figure 2 is a front view of a pair of exemplary doors mounted in the display case frame by means of a rail system having an upper rail assembly and a lower rail assembly. Figure 3 is a partial, bottom perspective view of the upper rail assembly of Figure 2 with the doors in a closed position. Figure 4 is a partial top perspective view of the upper rail assembly of Figure 2 with the doors in the closed position. Figure 5 is a partial top perspective view of the lower rail assembly with the doors in the closed position. Figure 6 is a partial bottom perspective view of the lower rail assembly with the doors in the closed position. Figure 7 is a partial bottom perspective view of the upper rail assembly with a first door in an open position. Figure 8 is a front view of another door assembly that includes a pair of doors mounted in a display case frame by means of another exemplary rail system that includes an upper rail assembly and a lower rail assembly. Figure 9 is a partial bottom perspective view of the upper rail assembly with the doors in the closed position. Figure 10 is a partial top perspective view of the lower rail assembly with the doors in a closed position. Figure 11 is a partial bottom perspective view of the upper rail assembly with the first door in an open position. Figure 12 is a schematic perspective view of an exemplary drive system that can be used with the sliding door system. Figure 13 is a schematic side view of the drive system in Figure 12. Figure 14 is a schematic perspective view of an exemplary drive system that can be used with the sliding door system. Figure 15 is a schematic side view of the drive system in Figure 14. Figure 16 is a schematic cross-sectional view of an exemplary drive system that can be used with the sliding door system. Before explaining in detail any of the constructions of the invention, it should be understood that the invention is not limited in its application to the construction details and arrangement of the components described in the following description or illustrated in the following drawings. The invention is capable of other embodiments and can be practiced or carried out in various ways. Furthermore, it is understood that the phraseology and terminology used herein are for descriptive purposes and should not be considered limiting. The use of the phrases "includes," "comprises," or "has," and variations thereof, herein means that they encompass the items listed below and their equivalents, as well as additional items. DETAILED DESCRIPTION OF THE INVENTION Figure 1 illustrates an exemplary refrigerated display case 10 that may be located in a supermarket, convenience store, or other suitable retail location (not shown) for presenting fresh food, frozen food, beverages, or other products 14 to consumers. The merchandise display case 10 includes a display case 18 that is defined by a base 22, an awning 26, opposite side walls 30, and a back wall 34. The display case 18 also includes an access opening 38 positioned opposite the back wall 34. The access opening 38 is defined by a display case frame assembly 42 that includes a display case frame 46. A plurality of doors 50 is attached to the display case frame 46 to provide access to the product 14 through the access opening 38.The area partially enclosed by the base 22, the awning 26, and the back wall 34 defines a product support area 54 (e.g., a product display area or volume 54) to support the product 14 in the display case 18. For example, the food product may be displayed on shelves or racks 58 that extend from the back wall 34 into the access opening 38 and are accessible to consumers through doors 50 adjacent to one front of the display case 18. As shown in Figure 1, the product 14 and the shelves 58 are visible behind the doors 50. The illustrated product display area 54 may be defined by one or more product display sections that are accessible through a corresponding door 50. The refrigerated merchandise display unit 10 also includes a refrigeration system (not shown) that is in communication with the display case 18 to provide a flow of refrigerated air to the product display area 54. The refrigeration system typically includes an evaporator located within an internal air passage to the display case 18. As is known in the art, the evaporator receives saturated refrigerant that has passed through an expansion valve. The saturated refrigerant evaporates as it passes through the evaporator as a result of absorbing heat from the airflow passing over it. The absorption of heat by the refrigerant allows the temperature of the airflow to decrease as it passes over the evaporator. The hot or gaseous refrigerant then exits the evaporator and is pumped back to one or more compressors (not shown) for reprocessing within the refrigeration system.The cooled airflow exiting the evaporator via heat exchange with the liquid refrigerant is directed through the rest of the air passage and introduced into the product display area 54 where the airflow will remove heat from and maintain the product 14 at the desired conditions. Figures 2 through 7 show that one or more of the 50 doors form part of an exemplary sliding door system 100. The sliding door system 100 includes a first door 102 and a second door 104, which are mounted on the display case frame 106 by means of a rail system. Each of the doors 102 and 104 is configured to move outward relative to the display case frame 106 and to slide or slide past the opposite door. This combined movement allows the doors 102 and 104 to open fully to provide access to the product support area, while simultaneously closing to form a hermetic seal between the refrigerated product support area and the external environment. As can be seen more clearly in Figures 2 to 4, each of the doors 102, 104 includes a door frame 108 surrounding one or more glass panels 110. A handle 112 is connected to each of the door frames 108. The doors 102, 104 are positioned opposite respective openings in the display case frame 106. The first door 102 and the second door 104 are coupled to the rail system having an upper rail assembly 114 and a lower rail assembly 116.Doors 102, 104 can be moved along the upper rail assembly 114 and the lower rail assembly 116 between a closed position in which both doors 102, 104 are positioned over their respective openings, a first open position in which the first door 102 slides outward from the display case frame 106 and laterally in front of the second door 104, and a second open position in which the second door 104 slides outward from the display case frame 106 and laterally in front of the first door 102. Doors 102, 104 can be moved manually or electrically using an actuator assembly 118. Doors 102, 104 are connected to the upper rail 114 and the actuator assembly 118 by means of a series of rollers connected to respective rods 120. The rods 120 extend from doors 102, 104 to the upper rail 114. In the illustrated embodiment, the rollers have a rotation axis that is coaxial to the longitudinal axis of the rod 120. Other embodiments may use other rotation axes. Referring to Figure 3, the first door 102 includes a first front roller 122, a first rear roller 124, and a first drive roller 126. The first front roller 122 and the first rear roller 124 are connected to the top rail 114, and the first drive roller 126 is connected to a first drive rail 128. The second door 104 includes a second front roller 130, a second rear roller 132, and a second drive roller 134. The second front roller 130 and the second rear roller 132 are connected to the top rail 114, and the second drive roller 134 is connected to a second drive rail 136. The drive assembly 118 can be configured to guide the doors 102 and 104 between different positions, either by manual operation, automatic operation, or a combination of both. As can be seen more clearly in Figures 3 and 4, the top rail 114 has a hollow body that defines a substantially C-shaped channel. The top rail 114 includes a center portion 138 that extends substantially parallel to the display case frame 106. A first door end 140 is located on one side of the center portion 138. The first door end 140 extends at an oblique angle to the center portion 138 and into the display case frame 106. In the closed position, the first door end 140 receives the first rear roller 124. A first door spur 142 extends from the center portion 138 at an oblique angle and into the display case frame 106. In the closed position, the first door spur 142 receives the first front roller 122. A second door end 144 is located on the other side of the center portion 138. The second end of door 144 extends at an oblique angle to the central portion 138 and towards the display case frame 106. In the closed position, the second door end 144 receives the second rear roller 132. A second door spur 146 extends from the central portion 138 at an oblique angle and towards the display case frame 106. In the closed position, the second door spur 146 receives the second front roller 130. A first gate 148 is located at a transition between the first gate spur 142 and the central portion 138. The first gate 148 can move between a first position in which it blocks a path between the first gate spur 142 and the central portion 138 and a second position in which it opens to the central portion 138 to provide a path between the first gate spur 142 and the central portion 138. A first stop 150 connects to the first gate via a first link 152. The first stop 150 is configured to move with the first gate 148 via the first link 152. A second gate 154 is located in a transition between the second gate spur 146 and the center portion 138. The second gate 154 can move between a first position in which it blocks a path between the second gate spur 146 and the center portion 138 and a second position in which it opens to the center portion 138 to provide a path between the second gate spur 146 and the center portion 138. A second stop 156 connects to the second gate 154 via a second link 158. The second stop 156 is configured to move with the second gate 154 via the second link 158. The actuator assembly 118 includes the first actuator rail 128 connected to a first linear actuator 160 and the second actuator rail 136 connected to a second linear actuator 162, such that the actuator rails 128 and 136 can be moved independently of each other. The actuator rails 128 and 136 each include a hollow body defining a substantially C-shaped channel that receives a respective actuator roller 126 and 134. The actuator rails 128 and 136 extend at an oblique angle from the center portion of the upper rail 114 and away from the display case frame 106. As shown in Figures 3 and 4, the first linear actuator 160 includes a first motor 163 positioned in a first motor housing 164 and a first rotary guide screw 166 connected to the first motor. The first drive rail 128 is keyed to the first guide screw 166 by means of a first drive bracket 168. Rotation of the first motor 163 causes rotation of the first guide screw 166, and translation of the first drive rail 128 relative to the display case frame 106. The second linear drive 162 includes a second motor 169 located in a second motor housing 170, and a second rotating guide screw 172. The second drive rail 136 is keyed to the second guide screw 172 by means of a second drive bracket 174. Rotation of the second motor 169 causes rotation of the second guide screw 172, and translation of the second drive rail 136 relative to the display case frame 106. ML / E / ZUZZ / Ul 100 / As can be seen more clearly in Figures 5 and 6, the gates 102, 104 are connected to the lower rail 116 by means of a series of lower rollers that are connected to respective lower rods 176. The lower rods 173 extend from the gates 102, 102 into the lower rail 116. In the illustrated embodiment, the lower rollers have a rotation axis that is coaxial to the longitudinal axis of the lower rod 173. Other embodiments may use a different rotation axis. The first door 102 includes a first front lower roller 178 and a first rear lower roller 180. The first front lower roller 178 and the first rear lower roller 180 connect to the lower rail 116. The second door 104 includes a second front lower roller 182 and a second rear lower roller 184. The second front lower roller 182 and the second rear lower roller 184 connect to the lower rail 116. The lower rail 116 has a body defining a groove. The groove includes a lower center portion 186 that extends substantially parallel to the display case frame 106. A first lower door end 188 is located on one side of the lower center portion 186. The first lower door end 188 extends at an oblique angle to the lower center portion 186 and into the display case frame 106. In the closed position, the first lower door end 188 receives the first lower rear roller 180. A first lower door spur 190 extends from the lower center portion 186 at an oblique angle and into the display case frame 106. In the closed position, the first lower door spur 190 receives the first lower front roller 178. A second lower door end 192 is located on the other side of the lower center portion 186.The second lower end of door 192 extends at an oblique angle to the lower center portion 186 and towards the display case frame 106. In the closed position, the second lower end of door 192 receives the second lower rear roller 184. A second lower door spur 194 extends from the lower center portion 186 at an oblique angle and towards the display case frame 106. In the closed position, the second lower door spur 194 receives the second lower front roller 182. A first lower gate 196 is located at the transition between the first lower gate spur 190 and the lower center portion 186. The first lower gate 196 can be moved between a first position in which it blocks a path between the first lower gate spur 190 and the lower center portion 186 and a second position in which it opens to the lower center portion 186 to provide a path between the first lower gate spur 190 and the lower center portion 186. A first lower stop 198 connects to the first lower gate 196 via a first lower link 200. The first lower stop 198 is configured to move with the first lower gate 198 via the first lower link 200. A second lower gate 202 is located at the transition between the second lower gate spur 194 and the lower center portion 186. The second lower gate 202 can be moved between a first position in which it blocks a path between the second lower gate spur 194 and the lower center portion 186, and a second position in which it opens to the lower center portion 186 to provide a path between the second lower gate spur 194 and the lower center portion 186. A second lower stop 204 connects to the second lower gate 202 via a second lower link 206. The second lower stop 204 is configured to move with the second lower gate 202 via the second lower link 206. Figure 7 shows the sliding door assembly 100 in its first open position, with the first door 102 moving in front of the second door 104. During an operating sequence, the first linear actuator 160 can be activated to move the first actuator rail 128 relative to the display case frame 106. The first gate 148 opens, allowing the first front roller 122 to move from the first door spur 142 to the center portion 138 of the top rail 114. The first gate 148 can be opened manually by means of the first front roller 122 or automatically via a control mechanism (e.g., rotary actuator, solenoid, etc.).As the first drive rail 128 moves, the first front roller 122 follows the path of the first door spur 142 and the first rear roller 124 follows the path of the first door end 140, moving horizontally with respect to the display case frame 106 and outward away from the display case frame 106. This disengages a seal between the first door 102 and the display case frame 106 and moves the first door 102 outward in front of the second door 104. To accommodate this movement, the first drive roller 126 moves inside the first drive rail 128 away from the display case frame 106.The first lower gate 196 follows similar movements with the first front lower roller 178 moving through and out of the first lower gate spur 190 within the lower center portion 186 and the first rear lower roller 180 moving through and out of the first lower gate end 188 within the lower center portion 186. During closing, the first motor 163 and the rotation of the first guide screw 166 are reversed, causing the first door 102 to move back over the first opening. The first front roller 122 engages with the first gate 148, which guides the first front roller 122 into the first door spur 142. As the first front roller 122 enters the first door spur 142, the first rear roller 124 engages the first door end 140, moving the first door 102 into the display case frame 106 and re-engaging the door seal. A similar movement follows when the second door 104 opens, moving within the central portion 138 of the upper rail 114 and the lower central portion 186 of the lower rail 116 and in front of the first door 102. Therefore, the first and second doors 102, 104 move at least partially along the same path to open and close. In some aspects, the opening and closing of the doors can be controlled by an electronic control system activated by user input. The control system may include one or more controllers configured to operate the linear actuators and gates. Control logic can be used to ensure that only one door opens at a time. In other aspects, the actuator assembly can be replaced with mechanisms that allow the doors to be operated entirely manually. In some aspects, doors 102 and 104 can be integrated with an automated storage and retrieval system (ASRS) where little or no user input is required to operate the rail system 100. Some configurations include a user access device that provides product location information and location notifications, directing the user to a specific product area. The doors can be activated to open when a user is near the location, allowing the user to retrieve the products. Once the product has been retrieved and the user releases the door, the door can close. In these configurations, the user can be a shopper in a store, a store employee, or a robotic system in a warehouse or storage facility. In some embodiments, the illustrated linear actuator can be replaced with other driving mechanisms, such as a belt drive system, a rack and pinion system, or other suitable mechanisms. Although two doors 102, 104 are shown with rail system 100, other configurations can be used, including one door, three doors, four doors, or more, as required. For example, a three-door system can be configured so that the two outer doors move over the middle door, and the middle door moves over one or more of the outer doors. Figures 8 through 11 show an exemplary embodiment of another sliding door system 210 that can be used for a refrigerated display case. The sliding door assembly 210 includes a first door 212 and a second door 214. Each of the doors 212 and 214 is configured to move outward relative to the display case frame 216 and to move in front of the opposite door. This combined movement allows the doors 212 and 214 to open fully to provide access to the product support area, while simultaneously closing to form a tight seal between the refrigerated product support area and the external environment. As best shown in Figure 8, each of the doors 212, 214 includes a door frame 218 surrounding one or more glass panels 220. A handle 222 is connected to each of the door frames 218. The doors 212, 214 are positioned opposite respective openings in the display case frame 216. The first door 212 and the second door 214 engage the rail system having an upper rail assembly 224 and a lower rail assembly 226. The doors 212, 214 can be moved along the upper rail 224 and the lower rail 226 between a closed position in which both doors 212, 214 are positioned over their respective openings, a first open position in which the first door 212 slides outward from the display case frame 216, and opposite the second door 214, and a second open position in which the second door 214 slides out from the display case frame 216 and laterally opposite the first door 212.Doors 212, 214 can be moved manually or electrically using an actuator assembly (not shown). As best shown in Figure 9, the doors 212, 214 are connected to the upper rail 224 by means of a series of rollers connected to respective rods 228. The rods 228 extend from the door into the upper rail 224. In the illustrated embodiment, the rollers have an axis of rotation that is perpendicular to the longitudinal axis of the rod 228. Other embodiments may use other axes of rotation. The first door 212 includes a first front roller 230 and a first rear roller 232. The first front roller 230 and the first rear roller 232 connect to the top rail 224. The second door 214 includes a second front roller 234 and a second rear roller 236. The second front roller 234 and the second rear roller 236 connect to the top rail 224. As shown in Figure 9, the top rail 224 has a hollow body defining a substantially C-shaped channel. The top rail 224 includes a center portion 238 that extends substantially parallel to the display case frame 216. A first door end 240 is located on one side of the center portion 238. The first door end 240 extends at an oblique angle to the center portion 238 and into the display case frame 216. In the closed position, the first door end 240 receives the first rear roller 232. A first door spur 242 connects to and extends from the center portion 238 at an oblique angle and into the display case frame 216. In the closed position, the first door spur 242 receives the first front roller 230. A second door end 246 is located on the other side of the center portion 238. The second end of door 246 extends at an oblique angle to the central portion 238 and towards the display case frame 216.In the closed position, the second door end 246 receives the second rear roller 236. A second door spur 248 connects and extends from the central portion 238 at an oblique angle and towards the display case frame 216. In the closed position, the second door spur 248 receives the second front roller 234. A first gate 250 is located at a transition between the first door spur 242 and the center portion 238. The first gate 250 includes a first linear channel 252 and a first curved channel 254. The first gate 250 can be moved between a first position in which the first linear channel 252 provides an extension through the center portion 238 and a second position in which the first gate 250 moves away from the display case frame 216 so that the first curved channel 254 provides a path between the first door spur 242 and the center portion 238. The first gate 250 can be moved by a linear actuator, for example, a solenoid actuator. A second gate 256 is located at the transition between the second door spur 248 and the center portion 238. The second gate 256 includes a second linear channel 258 and a second curved channel 260. The second gate 256 can be moved between a first position in which the second linear channel 258 provides an extension through the center portion 238 and a second position in which the second gate 256 moves away from the display case frame 216 so that the second curved channel 260 provides a path between the second door spur 248 and the center portion 238. The second gate 256 can be moved by a linear actuator, for example, a solenoid actuator. As best shown in Figure 10, the gates 212, 214 are connected to the lower rail by means of a series of lower rollers connected to respective lower rods 262. The lower rods 262 extend from the gates 212, 214 into the lower rail 226. In the illustrated embodiment, the lower rollers have an axis of rotation that is coaxial with the longitudinal axis of the lower rod 262. Other embodiments may use a different axis of rotation. The first door 212 includes a first front lower roller 264 and a first rear lower roller 266. The first front lower roller 264 and the first rear lower roller 266 connect to the lower rail 226. The second door 214 includes a second front lower roller 268 and a second rear lower roller 270. The second front lower roller 268 and the second rear lower roller 270 connect to the lower rail 226. The lower rail 226 has a body defining a groove. The groove includes a lower center portion 272 that extends substantially parallel to the display case frame 216. A first lower door end 274 is located on one side of the lower center portion 272. The first lower door end 274 extends at an oblique angle to the lower center portion 272 and into the display case frame 216. In the closed position, the first lower door end 274 receives the first lower rear roller 266. A first lower door spur 276 extends from the lower center portion 272 at an oblique angle and into the display case frame 216. In the closed position, the first lower door spur 276 receives the first lower front roller 264. A second lower door end 278 is located on the other side of the lower center portion 272.The second lower end of door 278 extends at an oblique angle to the lower center portion 272 and towards the display case frame 216. In the closed position, the second lower end of door 278 receives the second lower rear roller 270. A second lower door spur 280 extends from the lower center portion 272 at an oblique angle and towards the display case frame 216. In the closed position, the second lower door spur 280 receives the second lower front roller 268. A first lower gate 282 is located at the transition between the first lower door spur 276 and the lower center portion 272. The first lower gate 282 includes a first lower linear channel 284 and a first lower curved channel 286. The first lower gate 282 can be moved between a first position in which the first lower linear channel 284 provides an extension through the lower center portion 272 and a second position in which the first lower gate 282 moves away from the display case frame 216 so that the first lower curved channel 286 provides a path between the first lower door spur 276 and the lower center portion 272. The first lower gate 282 can be moved by a linear actuator, for example, a solenoid actuator. A second lower gate 288 is located at the transition between the second lower door spur 280 and the lower center portion 272. The second lower gate 288 includes a second lower linear channel 290 and a second lower curved channel 292. The second lower gate 288 can be moved between a first position in which the second lower linear channel 290 provides an extension through the lower center portion 272 and a second position in which the second lower gate 288 moves away from the display case frame 216 so that the second lower curved channel 292 provides a path between the second lower door spur 280 and the lower center portion 272. The second lower gate 288 can be moved by a linear actuator, for example, a solenoid actuator. Figure 11 shows the rail door assembly 210 in its first open position, with the first door 212 moving in front of the second door 214. During an opening sequence, the first gate 250 can be activated to move away from the display frame 216 to connect the first curved channel 254 with the center portion 238, allowing the first front roller 230 to move from the first door spur 242 to the center portion 238 of the top rail 224. The first front roller 230 follows the path of the first door spur 242, and the first rear roller 232 follows the path of the first door end 240, moving horizontally with respect to the display frame 216 and outward away from the display frame 216. This disengages a seal between the first door 212 and the display frame 216 and moves to the first door 212 outwards in front of the second door 214.The first lower gate 282 and the lower rollers follow similar movements with the first front lower roller 264 moving through and out of the first lower gate spur 276 within the lower center portion 272 and the first rear lower roller 266 moving through and out of the first lower gate end 274 within the lower center portion 272. During closing, the first front roller 230 will engage with the first gate 250 to guide the first front roller 230 into the first door spur 242. When the first front roller 230 enters the first door spur 242, the first rear roller 232 enters the first door end 240, which moves the first door 212 into the display case frame 216 and re-engages the door seal. In some aspects, the opening and closing of the doors can be controlled by an electronic control system activated by user input. The control system may include one or more controllers configured to operate the linear actuators and gates. Control logic can be used to ensure that only one door opens at a time. In other aspects, the actuator assembly can be replaced with mechanisms that allow the doors to be operated entirely manually. In some aspects, the doors can be integrated with an automated storage and retrieval system (ASRS) where little or no user input is needed to operate the 210 rail system. Certain configurations may include a user access device that provides product location information and location notifications to the user, directing them to a specific product area. The doors can be activated to open when a user is near the location, allowing them to retrieve the products. After the product has been retrieved and the user releases or moves away from the door, the door can close automatically. In these configurations, the user can be a shopper in a store, a store employee, or a robotic system in a warehouse or storage facility. Although two doors 212, 244 are shown with the rail system 210, other configurations can be used, including one door, three doors, four doors, or more, as required. For example, a three-door system can be configured so that the two outer doors move over the middle door, and the middle door moves over one or more of the outer doors. Figures 12 to 16 show schematic examples of different drive systems that can be used in sliding door systems 100, 210. The drive systems include a toothed timing belt along with a DC variable-speed motor or a DC stepper motor with a toothed drive gear that meshes with the teeth of the belt. These drive systems can be coupled or arranged in sliding door systems 100, 210 to move the doors 212, 244 between the open and closed positions. Figures 12 and 13 show an exemplary drive system 300 comprising a toothed belt 302 driven by a drive gear 304. A carriage 306 is connected to the belt 302. The carriage 306 can be connected to one of the doors 212, 244 (for example, by an actuator assembly) to move the door between the open and closed positions. The position of the carriage 306 can be fixed to the belt 302, and the movement of the belt 302 by means of the drive gear 304 can adjust the position of the carriage 306 to open and close the door. The drive gear 304 can be driven by a DC variable-speed motor or a DC stepper motor. As can be seen, each door 212, 244 has its own drive system 300 to move the corresponding door 212, 244 between the open and closed positions. Figures 14 and 15 show another exemplary drive system 400 that includes a toothed belt 402. A carriage 404 is connected to the belt 402. The carriage includes a drive gear 406 and a pair of idler wheels 408. The carriage 404 can be connected to one of the doors 212, 244 (for example, by an actuator assembly) to move the door between the open and closed positions. The position of the carriage 404 is variable relative to the belt 402, and the movement of the drive gear 406 adjusts the position of the carriage 404 relative to the belt 402 to open and close the door. The drive gear 406 can be driven by a DC variable-speed motor or a DC stepper motor. The idler wheels 408 keep the belt 404 engaged with the drive gear 406.One of the tension wheels 408 can be connected to a deflection mechanism (e.g., a spring or other mechanism that deflects wheel 408) that adjusts the position of tension wheel 408 relative to the drive gear 406 to maintain tension on the belt 404 and to allow movement of the slide 404 as the door moves toward and away from the display case frame. In some embodiments, the tension wheel 408 can be deflected along an axis tangential to the drive gear 406, although other tension directions are possible. As can be seen, each door 212, 244 has its own drive system 400 to move the corresponding door 212, 244 between the open and closed positions. Figure 16 shows another exemplary drive system 500 that includes a toothed belt 502 driven by a drive gear (not shown in Figure 16). A carriage 504 is connected to the belt 502. The carriage 504 can be connected to one of the doors 212, 244 (for example, by an actuator assembly) to move the door between the open and closed positions. The position of the carriage 504 can be fixed to the belt 502, and the movement of the belt 502 by means of the drive gear can adjust the position of the carriage 504 to open and close the door. The drive gear can be driven by a DC variable-speed motor or a DC stepper motor. The drive system components 500 are connected to an extruded rail 506. The rail 506 can include one or more connection features 508 that allow different components (for example, a cover or other decorative elements) to be connected to the drive system.As you can see, each door 212, 244 has its own drive system 500 to move the corresponding door 212, 244 between the open and closed positions. In some configurations, the drive system for each door may include combinations of the components described in relation to and illustrated in Figures 12 to 16. For example, the movable drive belt 302 with the fixed carriage 306 shown in Figures 12 and 13 can be used with a drive gear 304 working in combination with one or more idler wheels 408 that were described in relation to Figures 14 and 15. Other combinations of the drive system components are also possible.

Claims

CLAIMS 1. A refrigerated display comprising: a display case defining and separating a product display area from an environment, the display case having a frame defining one or more openings to the product display area; an upper rail connected to the display case and extending at least partially along the frame; a first door movably connected to the upper rail; and a second door movably connected to the upper rail, wherein the first door is configured to move between a closed position adjacent to the frame and a first open position in which the first door is positioned above the second door, and wherein the second door is configured to move between a closed position adjacent to the frame and a second open position in which the second door is positioned above the first door.

2. A refrigerated display unit comprising: a display case defining and separating a product display area from an environment, the display case having a frame defining one or more openings to the product display area; an upper rail connected to the display case and extending at least partially along the frame, the upper rail having a center portion, a first end extending from the center portion, a first spur extending from the center portion, a second end extending from the center portion, and a second spur extending from the center portion; a first door movably connected to the upper rail, the first door having a first front roller configured to move between the first door spur and the center portion and a first rear roller configured to move between the first door end and the center portion;and a second door movably connected to the upper rail, the second door having a second front roller configured to move between the second door spur and the central portion and a second rear roller configured to move between the second door end and the central portion, wherein the first door is configured to move between a closed position adjacent to the frame and a first open position in which the first door is positioned over the second door, and wherein the second door is configured to move between a closed position adjacent to the frame and a second open position in which the second door is positioned over the first door.

3. The refrigerated display case according to claim 2, further characterized in that a first gate is positioned between the first door spur and the central portion.

4. The refrigerated display case according to claim 3, further characterized in that the first gate rotates between a first position in which it blocks a path between the first door spur and the central portion and a second position in which it opens to the central portion to provide a path between the first door spur and the central portion.

5. The refrigerated display according to claim 3, further characterized in that the first gate includes a first linear channel and a first curved channel, and wherein the first gate moves between a first position in which the first linear channel is aligned with the central portion and a second position in which the first curved channel is aligned with the central portion.

6. The refrigerated display according to claim 2, further characterized in that the first door and the second door are connected to a lower rail.

7. The refrigerated display according to claim 2, further characterized in that the first door is connected to a first linear actuator and the second door is connected to a second linear actuator, and wherein the first door can be moved independently of the second door.

8. The refrigerated display according to claim 7, further characterized in that the first door includes a first drive roller and the first drive roller is connected to a first drive rail.

9. The refrigerated display according to claim 8, further characterized in that the first linear actuator includes a first guide screw keyed to the first actuator rail.

10. The refrigerated display according to claim 2, further characterized in that the first door and the second door are connected to a transmission belt.

11. The refrigerated display according to claim 10, further characterized in that the transmission belt includes a drive gear and a tension wheel, wherein the tension wheel is connected to a deflection member that deflects the tension wheel towards the drive gear.

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