Patent Publication Number: US-7908871-B2

Title: Systems and methods for dispensing product

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 10/726,815, filed Dec. 3, 2003, which is a Division of U.S. application Ser. No. 10/160,674 (now U.S. Pat. No. 6,698,228), filed Jul. 31, 2002. This application is also a continuation-in-part of U.S. application Ser. No. 10/359,834, filed Feb. 7, 2003. This application also claims the benefit of U.S. Provisional Applications No. 60/336,252, filed Nov. 2, 2001 (the benefit of which was claimed in U.S. Ser. No. 10/359,834), and No. 60/644,258, filed Jan. 14, 2005. The entire teachings of each of these references is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to systems and methods for producing and dispensing aerated and/or blended products, such as food products. While the invention may be used to produce a variety of products, it has particular application to the production and dispensing of frozen confections such as ice cream and frozen yogurt. Consequently, we will describe the invention in that context. It should be understood, however, that various aspects of the invention to be described also have application to the making and dispensing of various other food products. 
     BACKGROUND 
     Aerated frozen food products can be produced by mixing selected liquid ingredients with a prescribed volume of air and then freezing and dispensing the resultant mixture. The desirability of the finished product is often related directly to the manner in which, and to the degree to which, the air is metered and blended with the liquid ingredients of the mixture, referred to as overrun, and the manner in which the blended mix is frozen and then dispensed. Prior machines include many examples that dispense ice cream and other semi-frozen dairy products such as soft ice cream and frozen yogurt. 
     Conventionally, such machines are usually dedicated to dispensing one or two flavors of product and, in some cases, a combination of the two. For example, in an ice cream shop, there may be one machine with two separate freezing chambers for making and dispensing chocolate and vanilla ice cream, a second two-chamber machine for making and dispensing strawberry and banana ice cream, a third machine dedicated to making and dispensing coffee and frozen pudding flavors, and so on. The reason for employing multiple machines is that each chamber typically contains a volume of ice cream greater than is required for a single serving. In order to dispense a different flavor ice cream, that chamber must be emptied and cleaned before the new flavor can be made in that chamber and appear at the outlet of the dispenser. Additionally, the vat of pre-flavored mix from which the frozen product is made must also be clean enough to at least meet applicable health regulations. While high volume ice cream shops and confectionery stores may be able to accommodate several dispensing machines dispensing many different products and flavors, smaller sales outlets can usually only accommodate one or two such machines and are thus restricted in the number of flavors that they can offer to customers. 
     Further, because the product is typically formed in a quantity that is greater than that to be dispensed at any one serving, the excess product remains in the chamber after formation and until additional servings draw it down. The excess is thus subjected to further freezing, which promotes crystallization. Because of the relatively large quantity of the premixed flavors, and the continuous freezing of several quarts of the product, the freshness and palatability of the product may be adversely affected in outlets with relatively slow sales of the product. 
     Another disadvantage of many prior dispensers is that they have multiple interior surfaces and moving parts, as the cleaning and maintenance of those surfaces and parts at the end of each day or at intervals prescribed by local Health Department regulations is difficult and time-consuming. Each dispenser must be purged of any remaining product, and it&#39;s chamber walls, pumps and other internal parts cleaned thoroughly to prevent growth of bacteria that could otherwise contaminate the product being delivered by the dispenser. Not only is the cleaning operation expensive in terms of down time, it is also costly in terms of product waste. Furthermore, it can be an unpleasant task that is difficult to get employees to do properly. 
     While machines that dispense ice cream exist, until now no way has been found to provide a single machine capable of efficiently and economically making and dispensing different frozen food confections in a wide variety of flavors and in different formats, e.g., in a cup or cone. 
     SUMMARY 
     Described herein are systems and methods for producing and dispensing aerated and/or blended products, such as food products. One embodiment of an apparatus for producing a food product includes a frame to which is coupled a base-mix module, a flavor module, a flavor-selection assembly, a conduit configuration, and a food-preparation assembly. 
     The base-mix module supplies a base mix, while the flavor module provides flavoring. Both the base-mix module and the flavor module can include a plurality of holding bays, each bay being filled with a different base mix or flavor so as to allow selection from amongst the different base mixes and flavors. The base mixes and flavors can be contained in sealed packets that are loaded into the respective holding bays. A plurality of positive-displacement pumps can be coupled with the holding bays for the flavors so as to be able to receive the flavors as they are dispensed from the bays. The flavoring flows through a flavor-selection assembly and mixed with the base mix, which is aerated. Mix-ins, such as chips or nuts, can also be added from a mix-in module and mixed with the base mix. 
     After mixing and aeration, the flavored base mix is sprayed into a food-preparation assembly, where the mix is spread across a rotating freeze surface of a food-surface assembly. Refrigerant can be passed through the food-surface assembly to freeze the mix to form, e.g., ice cream. 
     The operation of the apparatus is governed by a main controller and a plurality of sub-controllers. Separate sub-controllers can be provided for the base-mix module, the flavor module, the flavor-selection assembly, and the food-preparation assembly, as well as for sub-components of these modules/assemblies. 
    
    
     
       BRIEF DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
         FIG. 1  is a front view of a food service machine according to one embodiment of the invention; 
         FIG. 2  is a perspective view of one embodiment of a base-mix module for use in the food service machine of  FIG. 1 ; 
         FIG. 3  is an exploded view version of  FIG. 2 ; 
         FIG. 4  is a perspective views of the base refrigeration subsystem of the base-mix module of  FIG. 2 ; 
         FIG. 5  is a schematic view of the control box for the base-mix module of  FIGS. 2-4 ; 
         FIG. 6  is a perspective view of one embodiment of a flavor module for use in the food service machine of  FIG. 1 ; 
         FIG. 7  is a front view and  FIG. 8  is an exploded schematic perspective view of  FIG. 6 ; 
         FIG. 9  is a back view of the flavor module of  FIG. 6 ; 
         FIG. 10  is perspective view of the back of the flavor module of  FIG. 6 ; 
         FIG. 11  is an exploded perspective view of a positive-displacement pump; 
         FIG. 12  is another exploded schematic perspective view of portions of  FIG. 6  including a linear drive; 
         FIG. 13  is an exploded schematic perspective view of one embodiment of a mix-ins module for use in the food service machine of  FIG. 1 ; 
         FIG. 14  a mix-in assembly used in the mix-ins module of  FIG. 13 ; 
         FIG. 15  is an exploded schematic perspective view of one embodiment of a primary refrigeration system and food preparation apparatus for use in the food service machine of  FIG. 1 ; 
         FIG. 16  is an assembled schematic perspective view of the primary refrigeration system and food preparation apparatus of  FIG. 15 ; 
         FIG. 17  is an exploded perspective view of a freeze-surface assembly of the food preparation apparatus of  FIG. 15 ; 
         FIG. 18  is an exploded perspective view of a rotating freeze-surface assembly (i.e., the food preparation apparatus) of  FIG. 15 ; 
         FIG. 19  is an assembled perspective view of the food preparation apparatus of  FIG. 18 ; 
         FIG. 20  is an exploded perspective view of a lower seal housing assembly of the food preparation apparatus of  FIG. 18 ; 
         FIG. 21  is an exploded perspective view of an upper seal housing assembly of the food preparation apparatus of  FIG. 18 ; 
         FIG. 22  is a cross-sectional view of a portion of the food preparation apparatus of  FIG. 15 ; 
         FIG. 23  is a top perspective view of one embodiment of a food cover assembly for use in the food service machine of  FIG. 1 ; 
         FIG. 24  is a bottom perspective view of the food cover assembly of  FIG. 23 ; 
         FIG. 25  is an exploded perspective view of the food cover assembly of  FIG. 23 ; 
         FIG. 26  is a top perspective view of the food cover assembly of  FIG. 23 ; 
         FIG. 27  is a sectional view of the pinion interface of the food cover assembly of  FIG. 26 ; 
         FIG. 28  is a sectional view of a level interface (including a squeegee) of the food cover assembly of  FIG. 26 ; 
         FIG. 29  is a sectional view of the forming/dispensing cylinder of the food cover assembly of  FIG. 26 ; 
         FIG. 30  is a top perspective exploded view of the food zone cover of  FIG. 23 ; 
         FIG. 31  is an illustration of one embodiment of the squeegee of  FIG. 23 ; 
         FIG. 32  is a schematic view of one embodiment of a flavor wheel assembly for use in the food service machine of  FIG. 1 ; 
         FIG. 33  is a cross-sectional view of the flavor wheel assembly of  FIG. 32 ; 
         FIG. 34  is an exploded top perspective view of the flavor wheel assembly of  FIG. 32 ; 
         FIG. 35  is a top perspective view of the flavor assembly wheel of  FIG. 32 ; 
         FIG. 36  is an exploded perspective view of one embodiment of a base aeration conduit assembly (with a connection for connecting to the flavor module) for use in the food service machine of  FIG. 1 ; 
         FIG. 37  is a front view of one embodiment of a process plate assembly, i.e., a process box, for use in the food service machine of  FIG. 1 ; 
         FIG. 38  is a perspective view of the process box of  FIG. 37 ; 
         FIG. 39  is a top view of the process box of  FIG. 37 ; 
         FIG. 40  is a right side view of the process box of  FIG. 37 ; 
         FIG. 41  is a top perspective view of one embodiment of a pneumatic module for use in the food service machine of  FIG. 1 ; 
         FIG. 42  is an exploded view and  FIG. 43  is a perspective view of the packing plate piston assembly of the process box of  FIG. 37 ; 
         FIG. 44  is an exploded view and  FIG. 45  are perspective views of the packing piston assembly of the process box of  FIG. 37 ; 
         FIG. 46  is an exploded view and  FIG. 47  is a perspective view of the pinion drive piston assembly of the process box of  FIG. 37 ; 
         FIG. 48  is a schematic illustration of one embodiment of the primary refrigeration system of  FIG. 15  and highlights a cooling loop; 
         FIG. 49  is the schematic illustration of  FIG. 48  highlighting the cooling loop in combination with a temperature-control loop; 
         FIG. 50  is the schematic illustration of  FIG. 48  highlighting a defrost loop; 
         FIG. 51  is a schematic illustration of the hot-gas valve control used with the system of  FIG. 48 ; 
         FIG. 52  is a schematic illustration of the liquid stepper control used with the system of  FIG. 48 ; 
         FIG. 53  is one embodiment of a timing diagram for operation of the primary refrigeration system during a serving sequence; 
         FIG. 54  is the schematic illustration of  FIG. 48  with each of the parts called out for use with a parts list; and 
         FIG. 55  is one embodiment of a serving sequence timing diagram for operation of the food service machine of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates to systems and methods for producing aerated and/or blended food products. While the invention may be used to produce a variety of products, it has particular application to the production of frozen confections such as ice cream and frozen yogurt. Consequently, we will describe the invention in that context. It should be understood, however, that various aspects of the invention to be described also have application to the making and dispensing of various other food products. 
     Referring to  FIG. 1  of the drawings, one embodiment of an apparatus for producing food according to the invention is a stand-alone unit  200  housed in a cabinet  19  having a top wall  19   a , opposite sidewalls  19   b  and  19   c , a bottom wall  19   d , and a middle separation wall  19   e  as well as a rear wall (not shown). In one embodiment these walls are merely covers. The front of the cabinet is open for the most part except for a low front wall  10  containing louvers to provide inlet air to a primary refrigeration unit, a base refrigeration unit and to pneumatics. The front opening into the cabinet may be closed by hinged doors  21   a ,  21   b ,  21   c  which may be swung between an open position wherein the doors allow access to the interior of the cabinet and a closed position wherein the doors cover the openings into the cabinet. Suitable means are provided for latching or locking each door in a closed position. 
     As shown in  FIG. 1 , a relatively large opening or portal  17  is provided in door  21   c  so that when the door is closed, the portal  17  provides access to a dispensing station  20  within the cabinet at which a customer may pick up a food product dispensed by the apparatus. Preferably, the portal is provided with a door so that the portal is normally closed blocking access to station  20 . A customer may select the particular product to be dispensed by depressing the appropriate keys of a control panel mounted in door  21   c  after viewing product availability. In the event the apparatus is being used as an automatic vending machine, the control panel may include the usual mechanisms for accepting coins, debit cards and currency and possibly delivering change in return. For advertising purposes, an illuminated display may be built into the front of a door, e.g., door  21   c.    
     Having described the housing and the doors for the housing, this description now turns to an overview of the apparatus  200  of  FIG. 1 . One embodiment of an apparatus for producing a food product includes: a housing/frame  19 ; a base-mix module  12  coupled to the frame and operative to provide refrigerated base mix and; a flavor module  14  coupled to the frame and operative to provide flavoring; a flavor-selection assembly  208  (shown in  FIGS. 32-34  and  37 ) coupled to the frame and having an outlet  118  and a plurality of, e.g., twelve, flavoring inlets  116   a ,  116   b , each inlet operative to receive a flavoring. The flavor-selection assembly  208  allows passage of a flavoring from a selected inlet to the outlet. The apparatus further includes a conduit assembly  120  (shown in  FIG. 36 ) having a proximal end  120   a  including a first opening  121  coupled to the base-mix module and a second opening  123  for receiving air. The conduit assembly  120  has a distal end  120   b  coupled to the outlet of the flavor-selection assembly  208 . The conduit assembly  120  combines base mix, air and flavoring to produce a flavored, aerated mix. 
     The apparatus for producing a food product can further include a mix-ins module  16  (shown in  FIG. 1 ). The apparatus includes a food-preparation assembly  22  (shown in  FIG. 1 ) coupled to the frame below a process box  24 . In one embodiment, the food-preparation assembly  22  includes a food-zone cover apparatus  93  (see  FIG. 23 ) adapted to receive the flavored, aerated mix from the distal end of the conduit assembly  120  and mix-ins from the mix-ins module  16 . The food-preparation assembly  22  then prepares food from the flavored aerated mix and mix-ins. 
     In one embodiment, the invention uses distributed computing to facilitate the testing, repair and/or replacement of the individual modules/components described above. More specifically, in one embodiment various modules/components have dedicated sub-controllers. Thus, in one embodiment, the base-mix module  12  has a dedicated base-mix-module sub-controller adapted to operate the base-mix module, the flavor module  14  has a dedicated flavor-module sub-controller adapted to operate the flavor module, the flavor-selection assembly has a flavor-selection assembly sub-controller adapted to operate the flavor-selection assembly, and the food-preparation assembly  22  has a dedicated food-preparation assembly sub-controller adapted to operate the food-preparation assembly  22 . In one embodiment, the sub-controllers can be conventional cards implemented in a combination of hardware and firmware and designed to comply with the controller area network open (CANopen) specification, a standardized embedded network with flexible configuration capabilities. The CANopen specification is available from CAN in Automation (CiA) of Erlangen, Germany, an international users&#39; and manufacturers&#39; organization that develops and supports CAN-based higher-layer protocols. 
     The apparatus further includes a control and power distribution box. The box includes an apparatus or main controller in communication with the base-mix-module sub-controller, the flavor-module sub-controller, the flavor-selection assembly sub-controller, and the food-preparation assembly sub-controller to provide instructions to the sub-controllers so as to operate the apparatus. Similarly, the mix-ins module  16  can include a dedicated mix-ins-module sub-controller in communication with the apparatus/main controller adapted to operate the mix-ins module  16 . In one embodiment, the main controller communicates with the sub-controllers over a bus using CANOpen, a controller area network-based higher layer protocol. CANOpen is designed for motion-oriented machine control networks, such as handling systems. 
     The main controller includes a digital I/O board with an associated CANOpen gateway, a CANOpen adaptor in communication with the CANOpen gateway, a motherboard in communication with the digital I/O board, the motherboard having an associated hard drive. The main controller further includes an Ethernet connection and two USB connectors in communication with the motherboard for providing external access to the motherboard. 
     The Base-Mix Module 
     With reference to  FIGS. 2 and 3 , one embodiment of a base-mix module includes: two base-mix holding bays  30   a ,  30   b ; two base mix conduits  32  each having a proximal end and a distal end (the proximal end adapted for coupling to a bag held in one of the base-mix holding bays); two pumps  26   a ,  26   b , e.g., peristolic pumps, each pump coupled to a base mix conduit, the base mix conduits couple to a conduit assembly (shown in  FIG. 36 ) forming a conduit assembly; a source of compressed air  244  (shown in  FIG. 42 ) couples to the base mix conduit, the source of compressed air controlled in part by an air-control valve  202   a  (shown in  FIG. 4 ). The air-control valve is operative to control the amount of air provided to the conduit assembly; and a base-mix-module sub-controller coupled to the pumps and operative to control the pumps and the air-control valve so that, when base mix is loaded into the base-mix holding bay, the base-mix-module sub-controller controls the amount of base mix and air injected into the conduit assembly. 
     More specifically and with reference to the embodiment illustrated in  FIGS. 4 and 5 , the base-mix-module sub-controller  159  includes four (4) cards, i.e., a digital input/output (I/O) board  153  with a CANOpen gateway  153 , an analog I/O board  154 , a first motor control board  156  for operating the first pump  26   a , and a second motor control board  158  for operating the second pump  26   b  (the pumps are shown in  FIG. 2 ). In one embodiment, the analog board and the motor control boards are daisy-chained to the digital I/O board. The purpose of the analog card is to receive thermocouple information from appropriately placed thermocouple(s), the thermocouple information allows the system to control the base refrigeration system to hold the base mix temperature within a specified temperature range, e.g., at or below about 41 degrees Fahrenheit (5° C.). 
     The Flavor Module 
     With reference to  FIGS. 6 to 12 , one embodiment of a flavor module  14  includes a plurality of flavor-packet holding bays  37  defined by brackets  44  and shelf (shelves)  45 . Each holding bay  37  holds a flavor packet  36 . The illustrated flavor module  14  includes a plurality of, e.g.,  12 , positive-displacement pumps  50  attached to pump frame  61  (shown in  FIGS. 7-9 ) to form two pump banks  50   a ,  50   b . Each pump  50  couples to a holding bay  37  via a fitting  42  and tubing  43 . An operator can attach the fitting  42  to a container (e.g., a bag) of flavoring and insert the flavor container into a holding bay  37 . Flavor flows from a flavor container through the fitting  42  and tubing  43  into a displacement pump  50 . Thus, displacement pumps  50  receive flavoring from flavor containers/packets held in the holding bays  37 . 
     With reference to the embodiment of  FIG. 11 , the pump  50  includes a piston  56  seated on top of the pump body  59  and supported by a piston spring  54 . The pump  50  further includes a check valve system. Each check valve includes a barb fitting  53 , a spring  55 , and a ball  57 . An inlet check valve  170  is on the front side  59 , i.e., the side having two orifices; and an outlet check valve  171  is on the bottom of the pump  50 . 
     The illustrated flavor module  14  includes a plurality of, e.g., twelve, electrical solenoids  48  coupled to slidable support plates  39   a ,  39   b  to form two solenoid banks  39   c ,  39   d . Support plate  39   a  slidably couples with two support shafts (one of which is designated  59   a  and the other of which is not shown). Similarly, support plate  39   b  slidably couples to two support shafts  59   b ,  59   c . Thus, the support plates can slide up and down on their support shafts. 
     The flavor module  14  includes a linear-drive motor  46  coupled to the slidable, support plates  39   a ,  39   b  to drive the support plates along the support shafts so as to bring the solenoid banks  36   c ,  39   d  in (or out of) contact with the pump banks  50   a ,  50   b . When the solenoid banks  39   c ,  39   d  come in contact with the pump banks  50   a ,  50   b , each solenoid  48  engages with an associated displacement pump  50  to cause at least one displacement pump  50  to dispense flavoring. The flavor module  14  further includes a flavor-module sub-controller in communication with each of the solenoids  48  and with the linear-drive motor  46 . The sub-controller controls each of the solenoids  48  and the linear-drive motor  46  so as to select and energize at least one solenoid  48  and to operate the linear-drive motor  46  to drive a slidable support plates  39   a / 39   b , moving the associated solenoid bank  39   c / 39   d  relative to the displacement pumps  50  such that an energized solenoid  48  causes an associated displacement pump  50  to dispense flavoring. More specifically, in the illustrated embodiment (see  FIGS. 9 ,  10  and  12 ), the flavor-module sub-controller includes a linear-drive board  13  for operating the linear drive  46 , a first solenoid-bank board  11  for operating the first solenoid bank  39   c , and a second solenoid bank board  15  for operating the second solenoid bank  39   d . Thus, in one embodiment the system uses a single precisely controlled conventional linear actuator to drive and pump a number of, e.g., twelve, different flavors. 
     With reference to  FIGS. 9 and 12 , linear-drive motor  46  includes a drive shaft  41  connected via a coupling assembly (including hubs  51   a ,  51   c  and disc  51   b ) to a male/female screw (not shown). The male part of the screw is on a coupler shaft  47  and the female part is on the housing. The male/female screw assembly provides precise position control. The precision control assembly is a conventional assembly. As noted above, support plates  39   a ,  39   b  support solenoids  48  to form solenoid banks  39   c ,  39   d . The coupler shaft  47  (see  FIG. 10 ) coming down from the linear motor  46  directly attaches to the support plates  39   a ,  39   b . As noted above, the top support plate  39   a  has two support shafts and the bottom support plate  39   b  has two support shafts. The support shafts connect to the support plates with precise bearings to keep the support plates parallel and square with each other so that as the linear-drive motor moves the support plates, it moves both plates simultaneously and in a controlled manner. In other words, in one embodiment the lead screw and motor assembly move the top plate  39   a  and the bottom plate  39   b  as a single unit. 
     In operation, when a user selects a flavor, the flavor module control scheme determines which pump e.g., of twelve available pumps—corresponds with a selected flavor/pump. The flavor module control scheme run by the main controller energizes the solenoid associated with the selected flavor. Energizing the appropriate solenoid  48  locks the solenoid rod  63  extending from the bottom of the solenoid  48 . All other solenoids are left in an un-energized state, which allows their rods to move up and down freely. Then the linear-drive motor (actuator)  46  drives the solenoid banks  39   c ,  39   d  down into contact with the pump banks  50   a ,  50   b . A flavor-module sub-controller, e.g., an appropriately programmed PC, provides instructions to the linear-drive motor (actuator)  46  on how fast to accelerate, how fast to move through the full acceleration and how long to operate which determines the displacement (length of stroke) of the single linear-displacement motor  46 . 
     The solenoid rod  63  for the energized solenoid  48  is stationary and all the other solenoid rods are free to move longitudinally, e.g., up and down. Thus only the solenoid rod  63  for the energized solenoid  48  pushes down on an associated pump piston  56 , which is resisted by spring  54 . The other 11 solenoids are at rest and their solenoid rods are thus free to move inside their associated solenoid bodies. In other words, when the metal rod inside the coil of the resting, i.e., non-energized, solenoid  48  encounters a pump piston  56  it merely slides in the solenoid body without displacing the piston  56 . 
     The displacement pumps  50  are already full of flavor because of a previous stroke. The drive shaft  41  of the linear-drive motor  46  downwardly displaces the support plates  39   a ,  39   b  and associated solenoid banks  39   c ,  39   d . As a result, the rod  63  of a selected/energized solenoid  48  pushes down on its associated pump piston  56  and, consequently, the associated pump  50  ejects flavor via its outlet to a flavor-selection assembly  208 , e.g., a flavor wheel (see  FIGS. 32-35 ). Pushing against piston  56  displaces the lower check valve  171 , and drives material out into a flavor-selection assembly  208 . Then, as the drive shaft  41  of the linear-drive motor (actuator)  46  moves back in a controlled manner (not an instantaneous release) to its home position, or base position, the check valve  171  on the bottom seats itself, and the inlet check valve  170  on the front of the pump  50  unseats itself creating a suction on an associated flavor storage bag and the pump  50  refills with flavoring. Thus, a singular linear-drive motor  46  pumps at least one of a plurality of, e.g., twelve, different flavors. 
     The Mix-Ins Module 
     With reference to  FIGS. 13 and 14 , one embodiment of a mix-ins module  16  includes a plurality of mix-in assemblies  65 . Each assembly  65  includes an auger block  60  forming a storage container orifice  69  (adapted to receive a mix-in storage container, such as bottle  58 ); an auger passage  71  coterminous with the container orifice  69  so as to allow flow from the container  58  through the container orifice  69  and then through the auger passage  71 ; and a dispensing orifice  73  coterminous with the auger passage  71  so as to allow flow through the auger passage  71  and then through the dispensing orifice  73 . Each assembly  65  further includes an auger  68  adapted to sit in the auger passage  71  of the auger block  60 , the auger  68  having an engagable end  67 . The mix-ins module  16  includes a plurality of drive assemblies  66  coupled to the engagable end of the augers  68  via auger drive  62  and operative to drive the augers  68 . 
     The mix-ins module  16  includes a trough assembly  64  having a collection slot  64   a  and a dispensing opening  64   b . The collection slot  64   a  is aligned with the dispensing orifices of the plurality of mix-in assemblies  65  to form a continuous passage therethrough. In one embodiment, the trough assembly  64  includes a trough cover  64   c . The trough assembly  64  receives mix-ins from the mix-in assemblies  65  and dispenses the mix-ins via dispensing opening  64   b . The mix-ins module  16  further includes a mix-ins-module sub-controller in communication with each of the mix-in assemblies  65 . The sub-controller controls the drive assemblies so that, when mix-ins containers are loaded into the mix-ins module  16 , the sub-controller drives the engagable ends  67  to turn the augers to dispense mix-ins. In the illustrated embodiment, the mix-ins-module sub-controller includes a motor control board  150  for operating a motor (not shown) that drives the drive assemblies. The mix-ins sub-controller further includes a CANOpen gateway board  151  in communication with the motor control board  150  and with the main controller via a bus. 
     Food Preparation Apparatus/Assembly 
     With reference to  FIGS. 15-22 , one embodiment of an apparatus for preparing food includes a food-surface assembly  70 , e.g., a freeze surface assembly, having a central axis and a periphery. The assembly, shown upside down in  FIG. 17 , includes an upper freeze plate  86  having a first face (i.e., a rotary freeze surface)  70   a  and a second face  172  (see  FIGS. 15-17 ). In one embodiment, the base material is aluminum, which facilitates heat transfer and is damage resistant and low weight relative to other practical materials. The first face, which is a highly polished nickel-plated surface, forms a non-stick rotary freezing surface that readily releases food products at low temperatures. The nickel plating provides strength and is conventional for food preparation applications. The nickel plating facilitates the system&#39;s ability to scrape ice cream off the surface without the ice cream sticking to the surface. 
     The second face  172  has a refrigerant channel  85  operative to pass refrigerant. The assembly includes a gasket  84  adapted to couple to the upper freeze plate  86  and operative to reduce cross flow of refrigerant. In one embodiment, the gasket  84  is made of a conventional type of neoprene specifically designed for refrigerant applications. The assembly  70  includes a lower freeze plate  82  coupled to the upper freeze plate  86  so as to sandwich the gasket  84  between the lower and upper freeze plates  82 ,  86 . The lower freeze plate  82  has a first face (not shown) and a second face  173 . The first face seals the refrigerant channel  85 , leaving the refrigerant channel  85  with an entrance orifice  82   a  and an exit orifice  82   b . A number of screws attach the bottom freeze plate  82  to the upper freeze plate  86 . Using a pattern of fastening that places screws adjacent to both sides of the refrigerant channel  85  helps to maintain the channel  85  and facilitates the function of gasket  84 . 
     Thus, the food-surface assembly  70  creates refrigerant passages for the refrigerant to enter the food-surface assembly  70 , to circulate around the entire channel  85  and then exit. Liquid refrigerant comes in to entrance orifice  82   a , moves through the entire channel and then exits via exit orifice  82   b . In an alternative embodiment, copper tubes are pressed into features machined into the upper freeze plate  86 . However, elimination of the copper tubing improves the heat transfer characteristic. The assembly  70  further includes an insulation plate  87  coupled to the lower freeze plate  82  and operative to provide insulation to the food-surface assembly  70 . In one embodiment, the insulation plate  87  is foam insulation that is glued to lower freeze plate  82 . The lower freeze plate  82  includes a number of orifices  82   c  that are not used for fastening, but that are used for pressure relief so that if the system does build up excessive pressure the pressure will be relieved via the orifices in the lower freeze plate  82 . 
     A thermocouple assembly  88  passes through lower freeze plate  82 , and is epoxied with silver filled epoxy to upper freeze plate  86  to within between 0.005 and 0.01 of an inch from the top of the rotary freeze surface  70   a . The thermocouple  88  is part of a system that measures the surface temperature and acts as one of a plurality of feedback loops for temperature control. 
     The apparatus for preparing food includes a drive shaft  265  (shown in  FIG. 22 ) coupled to the food-surface assembly  70 . With reference to  FIG. 15 , the apparatus further includes a drive motor  72  coupled to the drive shaft  265  and operative to rotate the drive shaft  265  causing rotation of the rotary surface about the central axis. More specifically, the drive motor  72  drives a pulley  74  that, in turn, drives a timing belt  76  to drive a pulley  78  attached to the drive shaft  265  (shown in  FIG. 22 ) to rotate the food-surface assembly  70 . The apparatus further includes a control box  80  (shown in  FIG. 15 ). The control box  80  contains a sub-controller coupled to the drive motor  72  and operative to control the drive motor  72  to control the rate of rotation of the food-preparation assembly  22 . The sub-controller can be a conventional motor control card that adheres to the CANOpen specification, such as motor control cards available from Elmo Motion Control, Inc. of Westford, Mass. 
     Thermocouple Slip Ring 
     With reference to  FIGS. 15-19 , a conventional slip ring assembly (typically used for transmitting power) is used for transmitting temperature measurements from the thermocouple assembly  88  to the sub-controller  80 . Thus, the system transmits low voltages through the slip ring assembly, which includes a slip ring  15   a , a first slip ring mount  77  and a second slip ring mount  83 . A plastic collar  81  helps to keep the slip ring assembly from freezing. If the slip ring assembly gets too cold, moisture from the air can condense on the slip ring assembly either causing the assembly to freeze up or resulting in errant temperature readings. Thus the plastic collar acts as an insulator between the slip ring  15   a  and the shaft  265  eliminating direct metal-to-metal contact. 
     The system, also uses a conventional seal  20  as a moisture barrier. The seal  20  keeps moisture out of the system and away from the shaft  265  and any housings to prevent moisture from being pulled into the shaft  265  and housings. Moisture in the system, e.g., on the shaft  265 , can freeze and ultimately lock the shaft  265 , i.e., prevent rotation of the shaft  265 . 
     Rotary Coupling 
     With reference to  FIGS. 17-22 , food-surface assembly  70  contains a fluid path  85 . The fluid path  85  has ends that are connected by a rotary coupling  261  to fluid lines leading to and from a primary refrigeration system. The rotary coupling includes an upper seal housing  204  and a lower seal housing  205 . The housings are modular housings that hold both support bearings and rotating refrigerant shaft seals. The seals themselves are conventional seals. 
     The modular design facilitates testing prior to assembly. Thus, system assemblers do not have to wait until the food-surface assembly  70  is installed inside the unit (shown as element  200  in  FIG. 1 ) to test for leaks. Having to wait for full assembly to test for leaks means that when a leak occurs the assemblers have to disassemble the unit, a time-consuming task. 
     More specifically, with reference to  FIG. 22 , moving from top to bottom of the figure, is shown a drive shaft  265  and a driven gear  78  and, further down, the upper housing module  204  including a large bearing  283 , a seal retainer plate  278  with a set of screws, a channel  275 , another retainer plate  283  and another bearing  283 . This configuration is repeated in the lower seal housing  205 . This configuration creates a refrigerant passage and seals the passage so that the refrigerant does not escape. 
     Thus, the upper seal housing  204  has an inlet  267  for receiving refrigerant. The refrigerant travels along the center of the shaft  265  via channel  269  where it is coupled to the food-surface assembly  70 . The refrigerant passes through the serpentine channel  85  milled in the upper freeze plate  86 . The refrigerant then exits the food-surface assembly  70  and travels along the shaft  265  via channel  273  and exits via outlet  271  in the lower seal housing  205 . 
     A mount  281  functions to mount the entire assembly  70  to the primary housing  19 . A second plate  279  with an associated nut and bolt assembly allows one to adjust for pitch and yaw to help maintain the physical relationship between the freeze plates and a process box/module  24  that resides above the food-surface assembly  70 . 
     With reference to  FIGS. 17 ,  18  and  22 , the food-surface assembly  70  further includes a lower shaft  203  and an upper shaft  210 . O-rings  202   a  provide a face seal between the upper shaft  210  and the inlet  82   a  and outlet  82   b . Similarly O-rings  202   b  provide a face seal between the lower shaft  203  and the upper shaft  210 . 
     Food Zone Cover 
     With reference to  FIGS. 15 , and  23 - 31 , one embodiment of a food-zone cover apparatus  93  includes a cover  90  operative to substantially enclose at least a portion of a substantially horizontal, flat rotary surface  73   a  (shown in  FIG. 16 ) to create a food zone. In the illustrated embodiment, the shape of the cover  90  mimics at least a portion of the rotary surface; e.g.,  FIG. 26  shows the shape of the periphery of the cover  90  to include a substantially circular arc  90   a , the ends of which are connected by a substantially straight edge  90   b . The food-zone cover apparatus  93  includes a final mixing conduit interface  92  coupled to the cover  90  and operative to receive liquid via a final mixing conduit  92   a  (shown in  FIG. 24 ), the final mixing conduit  92   a  is operative to deposit a selected amount of liquid product mix on the rotary surface  73   a  while the rotary surface  73   a  is rotating so that the liquid product mix spreads out on the rotary surface  73   a  and sets to form a thin, at least partially solidified, product body. More specifically, a conduit assembly couples to inlet  91  to provide aerated (typically flavored) liquid to the rotary freeze surface  73   a  below the cover  90 . 
     With reference to  FIG. 24 , the food-zone cover apparatus  93  includes a scraper  96  coupled to the cover  90  and supported above the rotary surface. The scraper  96  has a working edge  96   a  engaging the rotary surface  73   a  (see  FIGS. 15 and 16 ) while the rotary surface  73   a  is rotating to scrap the at least partially solidified product body into a ridge row on the rotary surface  73   a.    
     The apparatus includes a level  94 , e.g., a squeegee, coupled to the cover  90  and spaced above the rotary surface  73   a  to establish a gap. More specifically, the level  94  has a working edge  94   a  spaced above the rotary surface  73   a  to establish a gap between the working edge  94   a  and the rotary surface  73   a . With reference to  FIG. 31 , one embodiment of the squeegee includes feet  162   a ,  162   b  that maintain a specified gap between the working edge  94   a  and the rotary surface  73   a . The level  94  resides in proximity to the mixing conduit outlet  92   a  such that when the rotary surface  73   a  rotates in its intended direction the level  94  contacts the food product, e.g., aerated, flavored liquid, before the scraper  96  contacts it so as to level the food product to a specified height on the rotary surface  73  a while the rotary surface is rotating prior to the formation of the at least partially solidified product. In one embodiment, the gap/spacing between the working edge of the level  94 , e.g., squeegee, and the rotary surface  73   a  is between about 0.005 and 0.030 inches (i.e., between about 0.13 mm and 0.76) mm. In an alternative embodiment, the gap/spacing is between about 0.015 and 0.020 inches (i.e., between about 0.38 and 0.51 mm). 
     With reference to  FIG. 25 , the food-zone cover apparatus  93  includes a rack and pinion structure  110 ,  111  coup led to the cover  90 . The rack and pinion structure has a rack  110  and pinion  111 . The food-zone cover apparatus  93  includes a plow  100  coupled to the rack  110  and operative to scrape the ridge row from the rotary surface  73   a  as food product. The food-zone cover apparatus  93  includes a forming cylinder  98  coupled to the cover  90  and operative to receive the food product from the plow  100 . 
     With reference to  FIG. 29 , the apparatus includes a diaphragm  160  slidably coupled to the inside of the forming cylinder  98  so as to allow the diaphragm  160  to move longitudinally, i.e., up and down, within the cylinder  98 . Downward movement of the diaphragm  160  after insertion of food product in the forming/dispensing cylinder  98  forms the food product into a scoop. In the illustrated embodiment, the bottom portion of the diaphragm  160 , i.e., the portion of the diaphragm  160  that comes in contact with the food product, is semi-spherical in shape. However, the diaphragm  160  could take other shapes as is obvious to those of ordinary skill in the art. In the illustrated embodiment, the top of the diaphragm  160  has a mushroom-shaped structure  97   a  with a donut-shaped cutout  97   b  below the cap of the mushroom-shaped structure  97   a . The donut-shaped cutout  97   b  receives a diaphragm piston to allow movement of the diaphragm  160  from a first retracted position to a second, extended position. 
     The apparatus includes a packing/cleaning plate  113  rotatably coupled to the cover  90  via shaft  114 . With reference to  FIG. 29 , the packing plate  113  is positioned below the forming cylinder  98  to provide a food-product packing surface. In operation, a driven, rotating piston  102   a  rotates the packing plate  113  to clear the opening  98   a  of the forming cylinder  98 . Clearing the opening  98   a  allows the formed/packed ice cream serving to be pushed out of the forming cylinder  98  into a serving cup by longitudinal, i.e., downward, movement of the diaphragm  160  to its extended position. 
     With reference to  FIGS. 23 ,  26 ,  30 ,  37 , and  40 , one embodiment of the food-zone cover apparatus  93  interfaces with a process box  24  that includes a set of pistons  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  105   a , and  107   a , e.g., pneumatically driven pistons. In the illustrated embodiment, the process box  24  is located above the food-surface assembly  70 . More specifically, in operation, an operator places the food-zone cover apparatus  93  over the rotary surface  73   a  and the system lowers pistons  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  105   a , and  107   a  from the process box  24  to hold the food-zone cover apparatus  93 /cover  90  in place and to operate the elements of the food-zone cover apparatus  93 . Thus, in one embodiment, depending on local health department regulations periodic (e.g., daily) cleaning under normal circumstances can be limited to a region confined by the food-zone cover  90 . When cleaning is required, the process box  24  raises its pistons  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  5   a , and  107   a ; and an operator can remove the food-zone cover  90  to facilitate cleaning of the cover  90  and the rotary freeze surface  70   a.    
     Thus, in one embodiment, the food-zone cover apparatus  93  includes a level pneumatic piston interface assembly  106  coupled to the level  94  and operative to interface with at least one pneumatic piston  105   a  to allow control of the level  94 . In the illustrated embodiment, as shown in  FIGS. 26 ,  28  and  37 , the interface assembly  106  includes downforce interface  105  for interfacing with level downforce piston  105   a  and cleaning interface  103  for interfacing with cleaning piston  103   a . The level downforce piston  105   a  presses on the interface  105  including a level downforce shaft to cause the level  94  to engage with the rotary freeze surface  70   a . The cleaning piston  103   a  engages the level  94  to press the level  94  against the rotary freeze surface  70   a  for the purpose of cleaning the level  94  to reduce carry over from one serving to another. Carry over occurs when one flavor of food product, e.g., ice cream, used in a first serving contaminates a subsequently created serving. The feet  162   a ,  162   b  (shown in  FIG. 31 ) are flexible such that, with sufficient force, the feet  162   a ,  162   b  bend back and the level  94  presses against the rotary freeze surface  70   a  for cleaning. 
     The food-zone cover apparatus  93  includes a pinion pneumatic piston interface  107  coupled to the cover  90  and to the pinion  110   a  and operative to interface with a pneumatic piston  107   a . An electric motor  115  rotates the pinion piston  107   a  to cause rotation of the pinion  110   a  and consequently movement of plow  100  attached to rack  111 . 
     As noted above, the food-zone cover apparatus  93  includes a diaphragm pneumatic piston interface  97  coupled to the diaphragm  160  and operative to interface with a pneumatic piston  97   a  to allow control of the diaphragm  160  to form the food product. The food-zone cover apparatus  93  includes a packing plate pneumatic piston interface  102  coupled to the packing plate shaft  114  and operative to interface with a pneumatic piston  102   a . A motor rotates the piston  97   a  to allow operation of the packing plate  113 . 
     The food-zone cover apparatus  93  further includes a plurality of features  99 ,  101  in the cover  90  operative to interface with pneumatic pistons to hold the food-zone cover apparatus  93  against the rotating freeze surface  70   a . More specifically, depression  99  located on the periphery of the top  90   c  of cover  90  interfaces with hold down piston  99   a . Similarly depression  101 , also located on the periphery of the top of cover  90  but, when viewed from above, angularly displaced relative to depression  99 , interfaces with hold piston  101   a.    
     With further reference to  FIG. 23 , the illustrated food-zone cover apparatus  93  further includes a mix-ins receiving port  108  coupled to the cover  90 . The port  108  receives mix-ins from the dispensing orifice  73  of the mix-ins trough and distributes the mix-ins onto the liquid product after the level  94  has leveled the liquid food product onto the rotary freeze surface  70   a.    
     Flavor-Selection Assembly/Flavor Wheel 
     With reference to  FIGS. 32-34 , one embodiment of a flavor-selection assembly  208  includes a pump motor  210  connected to a pulley assembly  212 . The pulley assembly  212  includes a driving gear  212   c  coupled by a belt  212   b  to a driven gear  212   a . The driven gear  212   a  in turn couples via shaft  214   a  to a flavor-distribution-wheel assembly  214 . The flavor-distribution-wheel assembly  214  includes a wheel  214   c  with a plurality of fittings  214   b , which form a plurality of nozzles  216   a ,  216   b . In the illustrated embodiment, there are twelve nozzles in the wheel  214   c ; each nozzle is adapted to connect via tubing to an associated displacement pump  50  in the flavor module  14  described above. The flavor-distribution-wheel assembly  214  further includes an outlet  218  that couples to a common flavoring outlet conduit. With reference to  FIGS. 32-34 , the center  215  of the flavor wheel  214   c  has a channel  211  (shown in  FIG. 33 ). 
     The flavor-selection assembly  208  further includes a sub-controller  209  and a conventional sensor  213  coupled to the sub-controller  209 . The sub-controller  209  receives signals from the sensor  213  and controls motor  210  to position the flavor wheel  214   c  in a home position, e.g., rotating the flavor wheel  214   c  to align the channel  211  so that it is between two nozzles (such as nozzles  216   a  and  216   b ). In this position, no flavor can pass through to outlet  218 . 
     In operation, each flavor enters the flavor wheel  214   c  via one of the plurality of nozzles (e.g., nozzles  216   a ,  216   b ). When the system receives a flavor selection signal, the main controller instructs the flavor wheel sub-controller  209 , via bus  209   a , to drive motor  210  to rotate channel  211  a specified amount to bring channel  211  into alignment with the nozzle associated with the selected flavor, thereby allowing the flavor in the aligned nozzle to flow through to outlet  218 . 
     A fitting  217  also sits on top of shaft  214   a  to receive compressed air for cleaning out the outlet  118  and the outlet conduit. As shown in  FIG. 37 , in one embodiment, the flavor-selection assembly  208  resides in a process box  24  that sits above the food-zone cover apparatus  93  and the food-preparation assembly  22  (shown in  FIG. 1 ). 
     Conduit Assembly 
     With reference to  FIG. 36 , one embodiment of a conduit assembly  120  includes a proximal end  120   a  and a distal end  120   b . The proximal end includes a crow&#39;s foot junction  122  having three inlets  121 ,  123 , and  125  and an outlet  122   a . The first inlet  121  couples to a conduit, not shown, that in turn connects to conduit  32  via bulkhead conduit-to-conduit union  33  (see  FIG. 3 ). In other words, the first inlet  121  receives a first base mix via a conduit line attached to a first base mix container held in a first base mix tray  30   a  in the base-mix module  12  of  FIGS. 2 and 3 . Similarly, the third inlet  125  receives a second base mix via a conduit line attached to a second base mix container held in the second base mix tray  30   b  in the base-mix module  12 . The second inlet  123  couples via a one-way valve  129  and via tubing to a pneumatic module  242  (shown in  FIG. 41 ) for receiving air. The crow&#39;s foot junction  122  couples via a female luer lock  141  to tubing  120   c.    
     One embodiment of the conduit assembly&#39;s distal end  120   b  includes a barbed rotating male luer lock adaptor  139  coupled to the distal end of tubing  120   c . The adaptor  139  couples to a female luer lock  131 . The lock  131  couples to a first inlet of a two-inlet, one-outlet tee connection  137 . The second inlet couples via a male luer lock  135  to food grade tubing  133 , which in turn couples to the output of the flavor-selection assembly  208  of  FIGS. 32-34 . The outlet of the tee connection  137  couples via tubing  136  to mixing conduit  127 . This configuration allows the conduit assembly  120  to combine base mix, air and flavoring to produce a flavored, aerated mix at the output of mixing conduit  127 . In one embodiment, flavored aerated mix is ejected from a distal end of mixing conduit  127  onto the rotating freeze surface  70   a  of the food-surface assembly  70  shown in  FIGS. 15 to 19 . More specifically, with reference to  FIGS. 23 and 24 , the conduit assembly  120  couples to the food-zone cover apparatus  93  and sprays the mix from end  92   a  onto the rotating freeze surface  70   a . Element  92 , shown in  FIG. 23 , is the same as mixing conduit  127  shown in  FIG. 36 . 
     Process Box 
     With reference to  FIGS. 37-47 , which illustrate components in a process box, one embodiment of the process box  24  includes a conventional electrically operated pneumatic solenoid pump bank  232  (shown in  FIG. 39 ), such as those available form SMC Corporation of America of Indianapolis, Ind. In one embodiment, the solenoid pump bank  232  includes an air inlet  231  and a plurality of, e.g., seven, air outlets  233   a ,  233   b . The air inlet  231  couples to a conventional pneumatic module  242 , such as a Gast compressor system available from Ohlheiser Corporation of Newington, Conn., USA. The pneumatic module  242  provides regulated compressed air, e.g., at about 80 psi, to the air inlet  231  of the pump bank  232 . 
     As noted above with respect to the food-zone cover apparatus  93 , the process box  24  further includes a plurality of, e.g., seven, pneumatically driven piston assemblies  97   b ,  99   b ,  101   b ,  102   b ,  103   b ,  105   b ,  107   b . Each assembly has a piston  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  105   a ,  107   a  coupled to a pneumatic cylinder  97   c ,  99   c ,  101   c ,  102   c ,  103   c ,  105   c ,  107   c . Each pneumatic cylinder couples to an air output of the solenoid pump bank  232 . The solenoid pump bank  232  distributes air pressure to the pneumatic cylinders to operate the piston assemblies. Each piston  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  105   a ,  107   a  interacts with an associated piston interface  97 ,  99 ,  101 ,  102 ,  103 ,  105 ,  107  on the food-zone cover  90 . As noted above, a conventional pneumatic module  242  couples to the air inlet of the solenoid pump bank  232  and provides compressed air to the solenoid pump bank  232  so that the solenoid pump bank  232  can manage operation of the piston assemblies  97   b ,  99   b ,  101   b ,  102   b ,  103   b ,  105   b ,  107   b  to control interaction of the pistons  97   a ,  99   a ,  101   a ,  102   a ,  103   a ,  105   a ,  107   a  with associated piston interfaces  97 ,  99 ,  101 ,  102 ,  103 ,  105 ,  107  on the food-zone cover  90 . 
     With reference to  FIG. 41 , the pneumatic module  242  includes a holding tank  246  that provides food grade air to an air compressor  244 . The air compressor  244 , in turn, provides compressed air to a first regulator  248  and to a second regulator  250 . The first regulator  248  provides regulated air at a specified pressure, e.g., 80 psi, to the solenoid pump bank  232  in the process box  24 . The second regulator  250  provides food-grade air at a specified pressure, e.g., 40 psi, to the conduit assembly  120 . 
     Packing-Plate Piston Assembly 
     Having described the process box  24  in general, with reference to  FIGS. 42 and 43 , one embodiment of a packing-plate piston assembly  102   b  located in the process box  24  includes a post  274  coupled to a base  276 . The post  274  couples to a proximal end of an arm  268  via a pin  270 . A cylinder  102   c  couples to the base  276  and to a midsection of the arm  268  so as to raise and lower the arm  268 . A distal end of the arm  268  couples to a piston shaft  266  via a shaft end  272 . Thus, actuating the cylinder  102   c  lowers the shaft  266 . A gear  264  slides onto the shaft  266  and affixes to the shaft  266  in a concentric arrangement. The packing-plate piston assembly  102   b  further includes a motor  260 , which drives a pinion  262 . The driven pinion  262 , in turn, drives gear  264  to rotate the piston shaft  266 . 
     Thus, with reference to  FIGS. 42 ,  43  and  23 , in operation, the process-box sub-controller actuates the cylinder  102   c  to lower the piston shaft  266 , which engages piston  102   a  with piston interface  102 . The process-box sub-controller then energizes motor  260  to rotate the piston shaft  266 , which in turn rotates packing plate  113  to operate the packing plate  113 . 
     Packing-Piston Drive Assembly 
     With reference to  FIGS. 44 and 45 , one embodiment of a packing-piston drive assembly  97   b  located in the process box  24  includes a cylinder  97   c  mounted on a bracket  284 , which in turn is mounted on a bottom plate  286 . The packing-piston drive assembly  97   b  also includes a piston guide  288  that also mounts on the plate  286  so as to cover orifice  292 . A top plate  290  attaches to cylinder  97   c  and guide  288 . The packing piston  97   a  slidably engages with the bottom plate  286  and with guide  288  via orifice  292 . Attached to the cylinder  97   c  is a sliding cylinder plate  280 . Attached to the cylinder plate  280  is piston-attachment plate  282 , which also attaches to piston  97   a . Thus, when the process-box sub-controller actuates the cylinder  97   c , the cylinder  97   c  drives the piston  97   a  down to interact with interface  97  to operate the diaphragm  160  (described above with respect to the food-zone cover  90 ). In one embodiment, pin  290  (shown in  FIG. 38 ) engages with slot  97   b  (shown in  FIG. 29 ). 
     Rack-and-Pinion Drive Assembly 
     With reference to  FIGS. 46 and 47 , one embodiment of a rack-and-pinion drive assembly  107   b  located in the process box  24  includes a post  294  coupled to a base  296 . The post  294  couples to a proximal end of an arm  298  via a pin  297 . A cylinder  107   c  couples to the base  296  and to a mid-section of the arm  298  so as to raise and lower the arm  298 . A distal end of the arm  298  couples to a piston shaft  107   a  via a shaft end  295 . Actuating the cylinder  107   c  lowers the piston shaft  107   a . A gear  291  slides onto the shaft  107   a  and affixes to the shaft  107   a  in a concentric arrangement. The rack-and-pinion drive assembly  107   b  further includes a motor  289 , which drives a pinion  293 . The driven pinion  293  in turn drives gear  291  to rotate the piston shaft  107   a.    
     Thus, with reference to  FIG. 46 , in operation, the process-box sub-controller actuates the cylinder  107   c  to lower the piston shaft  107   a , which engages with piston interface  107 . The process-box sub-controller then energizes motor  289  to rotate the piston shaft  107   a , which in turn rotates pinion  110   a  to operate the plow  100  (pinion  110   a  and plow  100  are shown in  FIG. 25 ). 
     The other four piston assemblies, i.e.,  99   b ,  101   b ,  103   b ,  105   b , are conventional piston assemblies 
     Primary Refrigeration System 
     With reference to  FIG. 48 , one can describe the architecture of one embodiment of the primary refrigeration system  300  for the food-preparation assembly  22  by describing the loop(s) through which refrigerant travels during various modes of operation of the primary refrigeration system  300  under the control of the apparatus controller or a sub-controller governed by the apparatus controller. The controllers and sub-controllers of this apparatus can each include software stored on a computer-readable medium that is coupled with a processor; the software includes code for generating instructions for the components, described below, to carry out the various processes consequent to appropriate input being sent to the controller and sub-controllers. 
     Cooling 
     During cooling, i.e., when the primary refrigeration system  300  brings the food-surface assembly  70  down from ambient temperature to a set point, a cooling loop starts when the apparatus controller sends an instruction to the compressor  326  to start pumping to start the refrigerant gas flowing from the compressor  326  via a compressor discharge line  306  to a condenser  302 . Stated differently, the compressor  326  discharges refrigerant in the form of relatively hot and high-pressure gas into the condenser  302 . The controller also sends an instruction to start a fan that blows ambient air over the condenser  302  transferring heat in the gas to the ambient air; the fan blows the ambient air out of the unit. By cooling the hot gas, the hot gas is changed into a warm liquid. Under normal operation, the controller keeps a defrost solenoid  310  (an alternate loop) closed, which sends all of the refrigerant through the condenser  302 . 
     The liquid flows from the condenser  302  into a receiver  304 , which stores liquid for the refrigeration system  300 . The liquid flows through a filter drier  308 , which removes particulates, acid and moisture from the refrigerant. Then the liquid flows through a coil situated in the bottom of the suction accumulator  324 . The warm liquid in the coil boils off any liquid coming into the suction accumulator  324  via suction line  323 . 
     The liquid then flows from the suction accumulator  224  through a liquid solenoid  311 , which is governed by the controller to provide on/off control to a liquid thermal-expansion (TX) stepper valve  312 . The main (apparatus) controller, using a control algorithm with a wet/dry thermistor  326  as an input, controls the liquid flow into the food-surface assembly  70 . As noted above, the apparatus controller communicates via a bus to sub-controllers using a protocol such as the CANOpen protocol. In one embodiment, the primary-refrigeration-system sub-controller includes digital I/O board with an CANOpen gateway and two analog I/O boards. The sub-controller further includes first and second stepper controller boards daisy-chained to the digital I/O board. The controller and sub-controllers are also coupled (e.g., via wires or via wireless communication equipment) with each of the various sensors and control mechanisms in the system  300 . 
     The sub-controller feeds an excess of liquid into the food-surface assembly  70 , which keeps the wet/dry thermistor  326  at the food-surface assembly exit wet, i.e., the refrigerant passing the thermistor  326  is at least partially in a liquid state. As the liquid refrigerant passes through the food-surface assembly  70 , it boils, cooling the food-surface assembly  70 . More specifically, when the refrigerant passes through the liquid-stepper expansion valve  312 , the refrigerant experiences a pressure drop that turns the liquid into a cold liquid with some gas. The system injects the refrigerant in this state into the food-surface assembly  70 , where the cold liquid chills the food-surface assembly  70 . In the process of cooling the food-surface assembly  70 , much of the liquid boils off into a gas. The liquid and gas mixture leaves the food-surface assembly  70  and passes through the suction accumulator  324 . The excess liquid collects in the bottom of the accumulator  324  where it is boiled by the warm liquid coil. The refrigerant gas leaves the accumulator  324  and returns to the compressor  326 . 
     More specifically, the liquid stepper valve  312  is a conventional electronically controlled needle valve. The liquid stepper valve  312  passes the liquid refrigerant, via a liquid stepper discharge line  313  and via a rotary coupling  314   a , into the food-surface assembly  70 . A thermocouple  318  facilitates measurement of the temperature of the food-surface assembly  70 . The refrigerant then exits the food-surface assembly  70  via a rotary coupling  314   b  and travels back to suction accumulator  324  via a food-surface assembly discharge line  321 . In the illustrated embodiment, the discharge line  321  has a serpentine section  325  having a length of about 8 feet or more with a plurality of turns, e.g., four to eight bends. A pressure transducer  320  measures the pressure just prior, i.e., just upstream, to the serpentine section  325 . The thermistor  326 , mentioned above, measures the temperature in the discharge line on the downstream side of the serpentine section  325 . In one embodiment, the primary refrigeration system  300  uses a conventional refrigerant, such as R404A. However, the primary refrigeration system can use other refrigerants, such as R507. 
     After a period of time, the food-surface assembly  70  temperature sensor (e.g., thermocouple  88 ) measures that the food-surface assembly  70  has reached a set point. The thermocouple  88  communicates this reading to the sub-controller, which is programmed with software stored on a computer-readable storage medium. The processor in the controller, when processing this code in combination with the reading from the thermocouple  88 , initiates operation of a temperature-control loop. 
     Temperature Control 
     In order to artificially reduce the cooling capacity of the cooling loop (to maintain the set-point temperature), the controller causes a false load to be introduced. Thus, with reference to  FIG. 49 , the controller, in addition to governing the cooling loop (the inner loop, shown as loop  1 ), also governs a temperature-control loop (the outer loop, shown as loop  2 ), wherein hot gas from the compressor discharge line is sent through a hot-gas solenoid  327 . The hot gas then travels through a hot-gas stepper valve  322  (a proportionally controlled valve) and enters the cooling loop (loop  1 ) at a point  323  proximate to the beginning of the serpentine section  325 . In the illustrated embodiment the hot gas from the hot-gas stepper valve  322  enters the food-surface assembly discharge line  321  downstream from the location of the pressure transducer  320 . The controller governs the hot-gas stepper valve  322  to control the amount of hot gas that passes into the food-surface assembly discharge line  321 . 
     A hot-gas valve control scheme controls on temperature. If the temperature of the food-surface assembly  70 , as measured by thermocouple  88 , is below the set point, the controller sends an instruction to the hot-gas valve  322  to open by an amount that is proportional to how far the temperature of the food-surface assembly  70  is below the set point and proportional to how long the temperature of the food-surface assembly  70  has been below the set point. The software run by the controller utilizes a Proportional Integral and Derivative (PID) loop. Thus, the temperature-control loop (loop  2 ) applies a false load to the compressor  326  reducing the capacity of the cooling loop to cool the food-surface assembly  70 . 
     Modes/Control States 
     Pull Down 
     The controller governs the primary refrigeration system  300  to operate in a variety of modes. In pull-down mode, the mode in which the temperature of the food-surface assembly  70  is brought down from ambient temperature to a set point, the controller sends commands to the refrigeration system  300  to bring the temperature of the food-surface assembly  70  to the temperature that is needed to make ice cream. In one embodiment, the goal for pull-down mode is to achieve the set-point temperature, e.g., 12 degrees Fahrenheit, to within plus or minus one degree for 30 seconds. The pull-down modes starts with the hot-gas valve  322  in the off position, the liquid stepper valve  312  is at a boosted set point, e.g., about 280 steps where the valve  312  ranges from 0 to 380 steps (380 steps being completely open). Once the system is within a specified range, e.g., within 10 degrees, of the set-point temperature, the controller sets the liquid stepper valve  312  to a normal set value, e.g., 135 steps. 
     Idle/Standby 
     Once the system achieves the set point to within plus or minus one degree for 30 seconds, the controller (based on the communication of the temperature to it) instructs the system to transition from pull-down mode to idle mode. Idle mode is a mode in which the system is ready to make food product, e.g., ice cream. Once the system starts spraying liquid onto the food-surface assembly  70 , within less than a ten second interval, the primary refrigeration system  300  sees a large heat load because the primary refrigeration system  300  changes the state of the sprayed material from a liquid (mostly water) to an at least partially frozen food product, e.g., ice cream. In other words, in one embodiment, the primary refrigeration system  300  freezes a serving&#39;s worth of water, which involves a change of state of the water, requiring a large amount of energy in a very short period of time relative to maintaining the temperature of the food-surface assembly  70  in an idle state. 
     Once, in idle mode, the controller no longer controls the system based on a direct measurement of the temperature of the food-surface assembly  70 . Rather, the controller controls based on readings communicated to the controller from the pressure transducer  320 . 
     The pressure transducer  320  is used to determine the refrigerant temperature in the food-surface assembly  70 . The refrigerant for any given pressure only boils at one temperature. So if one measures the pressure in the food-surface assembly discharge line, then one can determine the temperature of the refrigerant. Pressure/temperature curves for various refrigerants, such as R404A and R507, are well known and readily obtained. The controller also controls the hot-gas stepper valve  322  based on readings received from the pressure transducer  320  rather than on readings from the thermocouple  88  because of the sensitivity of the temperature of the food-surface assembly  70  to the food product when food product is placed on the food-surface assembly  70  during an ice-cream-making mode. 
     The control scheme is self-correcting. Once the primary refrigeration system  300  transitions into idle mode, the controller determines saturation temperature, the boiling temperature of the refrigerant, based on the first measurement of pressure by the pressure transducer  320 . The controller then uses that saturation temperature as a set point. 
     The controller controls transition from pull-down mode to idle mode and controls the hot-gas valve  322  in idle mode in an effort to directly control the temperature. In contrast, the controller controls the liquid thermal-expansion stepper valve  312  so that the thermistor  326  indicates that the refrigerant is in a wet state, i.e., the refrigerant passing the thermistor  326  is at least partially in a liquid state. 
     In one embodiment, the controller causes flooding of the food-surface assembly  70  so that the system has excess liquid at the exit from the food-surface assembly  70 . Flooding the food-surface assembly  70  ensures that the food-surface assembly  70  is fully active with refrigerant boiling across the whole food-surface assembly  70 . To achieve a flooded food-surface assembly  70 , the controller monitor readings from the thermistor  326  to monitor the state of the refrigerant. 
     More specifically, in order to maintain the refrigerant in a wet state, the controller evaluates the resistance across the thermistor  326  periodically, e.g., every thirty seconds, and controls the liquid stepper valve  312  in response to those measurements. The thermistor  326  is a a type of resistor used to measure temperature changes, relying on the change in its resistance with changing temperature. 
     If one assumes that the relationship between resistance and temperature is linear, then one can state the following:
 
ΔR=kΔT
 
     where 
     ΔR=change in resistance 
     ΔT=change in temperature 
     k=first-order temperature coefficient of resistance 
     When the refrigerant transitions from a dry state to a wet state, it becomes colder. Assuming k is positive, when the temperature of the refrigerant becomes colder, the resistance measured by the thermistor  326  drops. Assuming a constant current source, a drop in thermistor resistance results in a voltage drop across the thermistor  326 . In one embodiment, a refrigerant dry state is defined as corresponding to a 5-volt drop, and a refrigerant wet state is defined as corresponding to a 2-3 volt drop. Thus, the controller monitors readings from the thermistor  326  periodically, e.g., every 30 seconds, and if the thermistor voltage drop does not indicate a wet state, the controller adjusts the liquid stepper valve  312  in an attempt to return the refrigerant to a wet state. 
     Stated differently, the controller uses the liquid stepper valve  312  to control the quantity of liquid at the wet/dry thermistor  326  to keep the food-surface assembly  70  flooded. When the liquid stepper valve  312  opens up, it increases the quantity of refrigerant in the system, which in turn raises the pressure in the food-surface assembly discharge line measured by the pressure transducer  320 , which in turn changes the temperature, which causes the hot-gas valve  322  to react. Thus, the liquid stepper valve  312  and hot-gas valve  322  systems are interdependent. 
     When a system designer designs a typical refrigerant system, generally the designer does not care much about where the position of liquid refrigerant is in the system, other than not wanting it in the compressor  326 . Other than that, all a designer is typically trying to do is to maintain some temperature in some environment. 
     In the present invention, it is helpful to maintain the food-surface assembly  70  in a flooded state. In other words, in one embodiment, the system attempts to ensure that at least some refrigerant remains in liquid state during the refrigerant&#39;s path through the serpentine channel in the food-surface assembly  70 . 
     Maintaining the food-surface assembly  70  in a flooded state has advantages. When a temperature change of a liquid, e.g., refrigerant, involves boiling, i.e., the state transition of a liquid to a gas, the temperature change involves a large energy transfer relative to a similar temperature change not involving a state transition. By maintaining the refrigerant in a liquid state, the controller maintains the ability to have a relatively large influence on the temperature of the food-surface assembly  70  in a relatively short amount of time. 
     In addition, maintaining a flooded state helps maintain temperature stability across the entire rotating freeze surface  70   a  [e.g., one embodiment of the food-surface assembly  70  has a 19-inch diameter (48-cm) freeze surface], and it provides the controller with relatively precise control of the temperature because the controller does not need to adjust the system for the possibility that the refrigerant might turn completely to gas in the evaporator/food-surface assembly  70 ; the refrigerant is always in an at least partially liquid state. In one embodiment, the controller maintain the temperature in the primary refrigeration system within +/−1 degree Fahrenheit (F) (+/−0.55° C.) and maintains uniformity of the temperature across the freeze surface  70   a  to within +/−1° F. 
     As noted above, when the system  300  first enters pull-down mode, the controller sets the liquid valve at a boosted set value, e.g., 280 steps in a range of 0-380 steps. Once the system is within a specified range, e.g., within 10 degrees, of the set-point temperature, the controller sets the liquid valve to a normal set value, e.g., 135 steps. Once the system transitions into idle mode, the controller adjusts the liquid valve setting to maintain the refrigerant at the thermistor  326  in a wet state. 
     Making Ice Cream 
     When the system  300  is in idle mode, it is ready to make ice cream. With reference to  FIG. 53 , at state  0 , a user indicates via user controls, e.g., a graphical user interface, that the user wants the unit to make a selected ice cream serving. In response, after a predetermined amount of time and before, the controller generates instructions to cause the spraying of food product onto the food-surface assembly  70 ; and the main controller enters a pre-cold stage, state  1 . The food product is only on the food-surface assembly  70  for about ten seconds. At state  1 , the main controller shuts down the hot-gas valve  322  and sets the liquid valve  312  to the boosted set value, e.g., about 280 steps. At state  2 , the food product is sprayed onto the food-surface assembly  70 . At state  3 , the food product, now in the form of frozen food product, e.g., ice cream, leaves the food-surface assembly  70 . 
     Once the food product leaves the food-surface assembly  70 , the controller monitors the temperature of the food-surface assembly  70 . The controller transitions the system  300  to the next state, state  4 , once the temperature of the food-surface assembly  70  is below the food-surface assembly temperature set point, e.g., 12° F. (−11° C.). If the food-surface assembly temperature is below the set point when the food product comes off the food-surface assembly  70 , then the controller automatically transitions the system to state  4 . Otherwise, the controller waits until the temperature of the food-surface assembly  70  is below the set point to intitiate the transition. The controller polls the thermocouple  88  periodically to monitor the food-surface assembly temperature, e.g., every 100 ms+/−30 ms, to determine when to make transitions that depend on the temperature of the food-surface assembly  70 . At the transition, the controller sends an instruction to the hot-gas valve  322  to open to the value it had at state  0 . A predetermined amount of time is taken for the hot-gas valve  322  to achieve the state  0  value. When the hot-gas valve  322  achieves the state  0  value, the controller transitions the system to state  5 . 
     The controller transitions the system to the next state, state  6 , when the controller determines, by monitoring the pressure transducer  320 , that the saturation temperature has recovered (e.g., when the saturation temperature is greater than or equal to the original saturation temperature set point plus some predetermined amount). Once the system is transitioned to state  6 , the controller instructs the liquid stepper valve  312  to return to the value it had at state  0 , the state  0  value or normal set point value (e.g., about 130 steps). As with the hot-gas valve  322 , a predetermined amount of time is utilized for the liquid stepper valve  312  to achieve the normal set-point value. 
     As noted above, the main controller communicates with sub-controllers including the primary-refrigeration-system sub-controller using a protocol such as the CANOpen protocol. One can refer to each sub-controller or module with which CANOpen communicates as a node. There are stepper controllers for the hot-gas valve  322  and for the liquid thermal-expansion valve  312 . There are different processes running on the host computer that will tell each different node what to do. 
     In one embodiment, the program that controls the main controller is written in the C programming language and follows the CANOpen specification to achieve communication with sub-controllers including the primary-refrigeration-system sub-controller. 
     Defrost Loop/Mode 
     With reference to  FIG. 50 , the defrost loop begins with refrigerant gas flowing from the compressor  326  through the discharge line  306  to the defrost solenoid  310 . The defrost solenoid  310  couples the compressor discharge line  306  with the liquid stepper discharge line  313 . The defrost mode thaws the food-surface assembly  70  out. In other words, in defrost mode the system raises the food-surface assembly temperature so that the food-surface assembly  70  can be cleaned. During defrost mode, the main controller closes the liquid solenoid  311  and the hot-gas solenoid  327  so there is no flow down the cooling loop and the temperature-control loop. The defrost solenoid  310  is open so refrigerant gas, which is hot from the compressor, is directed into the food-surface assembly  70 . The hot refrigerant gas returns through suction line  323  and through the suction accumulator  324  back to the compressor  326 . Thus, the defrost loop provides a loop of warm gas that flows through the food-surface assembly  70  warming the food-surface assembly  70  to a defrost set-point temperature. Over a period of time, e.g., three to five minutes, the food-surface assembly  70  warms up, when the food-surface assembly thermocouple  88  determines that the food-surface assembly  70  has reached a set point, e.g., 48 degrees Fahrenheit, the main controller terminates defrost mode and turns the defrost solenoid  310  off. Once the food-surface assembly  70  portion of the food-preparation assembly  22  has reached the defrost set-point temperature, an operator can then clean the food-surface assembly  70  and associated areas, e.g., the operator can wipe down the rotary freeze surface  70   a.    
     Depending on the requirements of the user of a system according to the invention, the user can instruct the system via user controls, e.g., a graphical user interface, to enter the defrost mode periodically, e.g., once a day typically at the end of the day. 
     Controls 
     With reference to  FIG. 51 , the primary refrigeration system  300  includes a hot-gas valve sub-controller  328  for controlling the temperature of the food-surface assembly  70 . As noted above, the sub-controller  328  monitors the surface temperature of the food-surface assembly  70  via thermocouple  318  and the suction pressure via pressure transducer  320 . 
     With reference to  FIG. 52 , the primary refrigeration system  300  includes a liquid stepper control  330  for controlling the flow of liquid refrigerant into the food-surface assembly  70 . As noted above, the control  330  monitors thermistor  326  and opens and closes the liquid stepper valve  312  to keep the thermistor  326  in what is referred to as a “wet zone.” 
     Control States 
     In one embodiment, the control states for the primary refrigeration system  300  are the following: initialization; stopped; pull down (startup); standby; ice cream cycle (7 steps); defrost; fault; and override/diagnostics. 
     “Initialization” is the process of turning the machine on. “Stopped” involves stopping the primary refrigeration system. “Pull down” occurs when the food-surface assembly  70  is above the set-point temperature, e.g., at ambient temperature, and the primary refrigeration system pulls the food-surface assembly  70  down to the set point. In one embodiment, the pull down process from room temperature takes about twenty minutes. 
     The primary refrigeration system  300  uses conventional proportional integral and derivative control. Proportional integral and derivative control is a form of control appropriate for a system that cannot move from a given environmental condition to the set point simply as a step function. In other words, proportional integral and derivative control is a form of control appropriate for a primary refrigeration system that cannot move the food-surface assembly  70  from 85° F. (29° C.) linearly and directly to 12° F. (−11° C.). Proportional integral and derivative control typically achieves a set point via a sinusoidal closed wave function. A primary refrigeration system using proportional integral and derivative control and having a 12° F. (−11° C.) set point starts with the food-surface assembly  70  at ambient temperature, e.g., 85° F. (29° C.). The temperature of the food-surface-assembly  70  starts coming down. The food-surface-assembly temperature passes below the set point, e.g., 12° F. (−11° C.). The food-surface-assembly temperature then oscillates up and down around the set point. Thus, the temperature of the food-surface assembly  70  as a function of time resembles a dampened harmonic oscillator oscillating around the set-point temperature. The amplitude of the oscillations becomes smaller and smaller and eventually the wave dampens itself out. 
     The idle/standby, ice cream cycle/making, and defrost states/modes were described above. The other states are conventional states used in controlling food preparation machines. 
     With reference to  FIG. 54 , many of the elements of the primary refrigeration system are conventional. The following is a list of parts and associated manufacturers and suppliers for one embodiment of the primary refrigeration system. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
               
               
                   
                   
                   
                   
                 Supplied 
                 DCI 
                 Lydall 
               
               
                 Item 
                 Description 
                 Manufacturer 
                 Part number 
                 By 
                 Part # 
                 Part # 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 326, 
                 Condensing 
                 Tecumseh 
                 AWA2464ZXDXC 
                 DCI 
                 61872 
                   
               
               
                 302 &amp; 
                 Unit 
               
               
                 304 
               
               
                 308 
                 Filter drier 
                 Sporlan 
                 C-083-S 
                 Lydall 
                 61872 
                 9476 
               
               
                 329 
                 Sight glass 
                 Sporlan 
                 SA13S 
                 Lydall 
                 68119 
                 2546 
               
               
                 312 
                 TX valve 
                 Emerson Flow 
                 ESVB-1 24 
                 DCI 
                 61873 
               
               
                   
                   
                 Control 
               
               
                   
                 Connector, 
                 Alco 
                 62093 
                 DCI 
                 61874 
               
               
                   
                 stepper, 4 wire 
               
               
                   
                 for TX 
               
               
                 322 
                 Hot-gas valve 
                 Sporlan 
                 SEI 11 3X4 ODF- 
                 Lydall 
                 72525 
                 13072 
               
               
                   
                   
                   
                 10-S 
               
               
                 324 
                 Suction 
                 Refrigeration 
                 HX 3738 
                 Lydall 
                 72529 
                 32660 
               
               
                   
                 accumulator 
                 Research 
               
               
                 326 
                 Thermistor 
                 Parker 
                 040935-04 
                 DCI 
                 72539 
               
               
                   
                 Adapter 7/8 
               
               
                   
                 Thermistor 
                 Parker 
                 040930-150 
                 DCI 
                 72537 
               
               
                 310 
                 Solenoid 
                 Sporlan 
                 E5S130 
                 Lydall 
                   
                 33101 
               
               
                   
                 valve 1- 
               
               
                   
                 Defrost 
               
               
                   
                 Solenoid coil 
                 Sporlan 
                 MKC1-208- 
                 DCI 
                 74169 
               
               
                   
                   
                   
                 240/50-60 
               
               
                 331 
                 5/8 Ball valve 
                 Various 
                   
                 Lydall 
                 72890 
                 6095 
               
               
                   
                 refrigeration 
               
               
                   
                 grade 
               
               
                 333 
                 7/8 Ball valve 
                 Various 
                 A17264 
                 Lydall 
                 74004 
                 6096 
               
               
                   
                 refrigeration 
               
               
                   
                 grade 
               
               
                 314A 
                 5/8 Tube 
                 Parker 
                 12-10L0HB3-S 
                 DCI 
                 72639 
               
               
                   
                 fittings (2) 
               
               
                   
                 Liquid hose 
                 Parker 
                 73499 
                 DCI 
                 73499 
               
               
                 314B 
                 5/8 Tube 
                 Parker 
                 12-10L0HB3-S 
                 DCI 
                 72639 
               
               
                   
                 fittings (2) 
               
               
                   
                 Suction hose 
                 Parker 
                 73501 
                 DCI 
                 73501 
               
               
                 321 
                 Suction line 
                 Lydall 
                 32722 
                 Lydall 
                 74013 
                 32722 
               
               
                   
                 mixing line 
               
               
                   
                 7/8 
               
               
                 323 
                 Suction riser 
                 Lydall 
                 32724 
                 Lydall 
                 74012 
                 32724 
               
               
                   
                 7/8 
               
               
                 335 
                 Suction line 
                 Lydall 
                 32723 
                 Lydall 
                 74009 
                 32723 
               
               
                   
                 7/8 
               
               
                 320 
                 Pressure 
                 MSI 
                 MSP-300-250-P-4- 
                 DCI 
                 73021 
               
               
                   
                 transducer 
                   
                 N-1 
               
               
                 327 
                 Solenoid 
                 Sporlan 
                 B6S1 
                 Lydall 
                   
                 33102 
               
               
                   
                 valve 2-Hot 
                   
                 1/2ODFx5/8ODM 
               
               
                   
                 gas 
               
               
                 311 
                 Solenoid 
                 Sporlan 
                 E5S130 
                 Lydall 
                   
                 33101 
               
               
                   
                 valve 3-Liquid 
               
               
                 337 
                 Pressure 
                 Emerson Flow 
                 PS1-X5K 
                 Lydall 
                   
                 5704 
               
               
                   
                 switch 
                 Control 
               
               
                   
                 Refrigerant 
                   
                   
                 Lydall 
                 74016 
                 28124 
               
               
                   
                 R404a 
               
               
                   
               
            
           
         
       
     
     DCI is DCI Automation, Inc. of Worcester, Mass. Lydall is Lydall, Inc. of Manchester, Conn. Tecumseh is Tecumseh Products Company of Tecumseh, Mich. Sporlan is Sporlan Valve Company of Washington, Mo. Parker is the climate and industrial controls group of Parker Hannifin Corporation located in Broadview, Ill. Emerson Flow Control is the flow controls division of Emerson Climate Technologies of St. Louis, Mo. Refrigeration Research is Refrigeration Research, Inc. of Brighton, Mich. 
     Timing Diagrams 
     Having provided an overview of the structure and operation of the unit  200 , shown in  FIG. 1 , and having described the structure and operation of the components that make up that unit, a description of the timing diagrams provided in  FIG. 55  for various system sequences is now provided. Each of the timing diagrams lists the following items (and operational state) on the vertical (y) axis: 1 st  cover hold-down (up/down); 2 nd  cover hold-down (up/down); packing plate engagement (up/down); packing plate position (delivery/forming/home); pinion engagement (up/down); horizontal pinion drive (forward/back/home); vertical forming piston (up/neutral/down); cup lift (up/neutral/down); leveling squeegee cleaning (up/down); leveling squeegee downforce (up/down); base pump (running/stopped); aeration (on/off); flavor pump (running/stopped); flavor purge (on/off); and mix-in motor (running/stopped). The horizontal (x) axis denotes time. Thus, the timing diagrams indicate the time of state transitions during various system activities for the items listed on the vertical axis. 
     The labels, “cover hold-down #1,” “cover hold-down #2,” “packing plate engagement,” “packing plate position,” “pinion engagement,” “horizontal pinion drive,” “vertical forming piston,” “cup lift,” “leveling squeegee cleaning,” and “leveling squeegee downforce,” refer to the up/down or engagement state of the pistons shown in  FIGS. 37-40  and  42 - 47 . The main controller, via the process sub-controller, controls the pump bank and piston assembly motors to achieve the desired states. Similarly, the labels, “base pump,” “aeration,” “flavor pump,” “flavor purge,” and “mix-in motor,” respectively refer to the on/off or running/stopped states of the base pump, the food grade portion of the pneumatic module, the flavor pump, the flavor purge portion of the pneumatic module, and the mix-ins motor. The main controller either directly and/or via various component sub-controllers controls the states of these components. 
     With reference to  FIG. 55 , one embodiment of a sequence for serving food product, e.g., ice cream, starts in the following state: cover hold-down #1 (down); cover hold-down #2 (down); packing plate engagement (down); packing plate position (forming); pinion engagement (down); horizontal pinion drive (back); vertical forming piston (up); cup lift (down); leveling squeegee cleaning (up); leveling squeegee downforce (up); base pump (stopped); aeration (off); flavor pump (stopped); flavor purge (off); and mix-in motor (stopped). A variety of conventional sensors determine that the food service machine proceeds through the following process prior to initiating the serving sequence: delivery door interlock (disengaged); delivery door sensor (open); user installs cup; cup sensor (yes); delivery door sensor (closed); deliver door interlock (engage); and start freeze surface rotation. 
     The illustrated serving sequence is the following, each numbered step occurring later in time than the prior numbered step: 1) at time TS2 the leveling squeegee moves down; 2) the base pump starts running, and the aeration is turned on; 3) the flavor pump starts running (at this point, the mixing conduit is spraying a mixed, aerated composition (typically flavored mix onto the rotating freeze surface); 4) the mix-in motor starts running (causing the mix-ins module  16  to deposit selected mix-ins onto the leveled food product sitting on the rotating freeze surface); 5) the base pump stops; 6) the flavor pump stops, and the flavor purge is turned on; 7) the flavor purge ends, and the aeration ends; 8) the mix-in motor stops; 9) the leveling squeegee downforce piston disengages (moves up); 10) the leveling squeegee cleaning piston moves down to cause cleaning of the squeegee; 11) the leveling squeegee cleaning piston moves up, the cup lift moves up, and the freeze surface stops rotating (the food product is now accumulated as a ridge row on the scraper of the food zone cover); 12) the horizontal pinion drive moves to the forward position (pushing the food product into the forming cylinder); 13) the vertical forming piston moves down (to pack the food product); 14) the vertical forming piston moves to a neutral position; 15) the packing plate position moves from forming to delivery; 16) the product deposits into a cup; 17) the cup lift moves from up to neutral position; 18) the packing plate position moves from delivery to forming; and 19) a variety of conventional sensors determine that the food service machine proceeds through the following process: (a) delivery door interlock (disengage); (b) delivery door sensor (open); (c) the user removes the cup; (d) cup sensor (clear/no cup); (e) delivery door sensor (close); and (f) delivery door interlock (engaged). The serving sequence completes with the following steps: 20) the packing plate position moves from forming to home and then to delivery to achieve a wiping action and the vertical forming piston moves from down to up; 21) the horizontal pinion drive moves from forward to home and then, after a period, to back position; 22) the vertical forming piston moves from up to down and then, after a period, to up position again; 23) finally, the packing plate position moves from delivery to forming. 
     Having thus described at least one illustrative embodiment of the invention, various alterations, modifications and improvements are contemplated by the invention. Such alterations, modifications and improvements are intended to be within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention&#39;s limit is defined only in the following claims and the equivalents thereto.