Abstract:
An inductive drive motor is shown wherein a magnetic rotor is positioned within an enclosed space defined by a housing surface. A stator is positioned around the surface in close contact therewith wherein the rotor is positioned substantially centrally thereof. The stator includes windings around the perimeter thereof wherein a phased flow of current therein provides for the creation of a magnetic field for rotatively driving the rotor. The rotor can be connected to various devices for mixing or scraping various liquid contents within the enclosed space. The stator windings are completely encapsulated in a corrosion resistant material, such as, a suitable plastic. Thus, the inductive drive motor has an extended life when used in corrosive environments.

Description:
[0001]    The present application is a co-pending continuation-in-part of U.S. patent application Ser. No. 09/079,683, filed May 15, 1998, which was a co-pending continuation-in-part of U.S. patent application Ser. No. 08/987,395, filed Dec. 9, 1997. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to electrical motors, and more specifically to methods and structure for the protection of such motors when exposed to high levels of water condensation thereon.  
         BACKGROUND  
         [0003]    FCB making and dispensing machines are known in the art and generally utilize a freezing cylinder for producing a slush beverage therein. An evaporator coil is wrapped around the exterior of the cylinder for cooling the contents thereof. A scraper mechanism extends along the central axis of the cylinder and is rotated to scrape thin iced or frozen layers of the beverage or food product from the internal surface of the cylinder. A carbonator tank is used to produce carbonated water by the combination therein of water and pressurized carbon dioxide gas (CO 2 ). The carbonated water and a syrup are then combined in the desired ratio and introduced into a separate blender bottle. The properly ratioed beverage is then delivered from the blender bottle into the freeze cylinder. A problem with this approach concerns the warming of the contents of the carbonator and blender bottle wherein high pressures are required to maintain the desired level of carbonation at such elevated temperatures.  
           [0004]    An ongoing problem with FCB machines, and related to the foregoing, is the amount of cooling that is required to make and maintain a beverage in a semi-frozen state. This cooling demand is especially great during times of high use when, as drinks are being dispensed, new ambient temperature water and syrup are continually being added to the cylinder from the blender bottle. A strategy has long been needed to provide for high draw capacity in an FCB machine without resorting to the expedient of requiring ever larger refrigeration compressors and systems with their concomitant increase in machine purchase cost, cost of operation and noise of operation. A further problem with prior art FCB machines concerns their mechanical or design complexity. This complexity, in terms of numbers of parts, adds cost with respect to manufacture and maintenance, and also negatively impacts reliability. Accordingly, it would be very desirable to have an FCB machine that is less expensive and easier to manufacture and maintain.  
           [0005]    A further drawback to FCB machines is the fact that the scraper mechanism inherently requires a shaft portion thereof to extend through a cylinder end for connection to a drive motor, thereby requiring a dynamic seal. This requirement stems from the fact that the drive mechanism is exterior of the cylinder and can not come into direct contact with the food product therein. Naturally, such seals are subject to wear and consequent leaking, especially where the beverage contents are under pressure, as is the case for a frozen carbonated beverage. Major service problems with such machines are related to failed or leaking scraper shaft seals. Accordingly, it would be very desirable to be able to eliminate such seals, yet have a scraper drive mechanism that does not create food compatibility/contact problems, and that has sufficient strength to operate the scraper against the considerable resistance it encounters when producing the desired frozen food product.  
           [0006]    Semi-frozen food product making and dispensing equipment employs the use of electrical motors to rotate the scraping mechanism located within the freeze cylinder. Liquid food product is delivered to the refrigerated cylinder and frozen fractions thereof are harvested form the interior of the cylinder by the rotating scraping mechanism. Thus, over time, the food product becomes more viscous having a larger semi-frozen fraction thereof. A particular pre-set viscosity/level is maintained by alternately turning the refrigeration of the cylinder on and off, once the desired level of food product thickness is achieved.  
           [0007]    As the brushless drive motor described herein is in close physical heat exchange contact with the freezing cylinder, the stator thereof can become quite cold. As a result thereof, there can be significant water condensation thereon. This condensation can can lead to oxidation of the windings thereof and eventual failure of the motor. Accordingly, it would be very desirable to have a magnetic drive mechanism for a semi-frozen food product dispenser that is resistant to the detrimental effects of condensation and any other corrosive action thereon.  
           [0008]    In prior art frozen food product machines it is also known to deliver the beverage into the cylinder through the side wall thereof. However, since the evaporator is wound around the side wall, there is interference there between, thus limiting the amount of surface area that can be cooled. Also, the entire perimeter of the cylinder is typically encased in a foam insulation. Thus, access to the liquid beverage delivery tube for repair is complicated. In addition, the side wall inlet approach complicates the process of manufacturing the dispensing machine. Accordingly, it would be desirable to have a semi-frozen food product making and dispensing machine wherein the liquid food product delivery line and inlet do not compromise the amount of cooling that can be applied to the cylinder and that permit easy to manufacture and repair.  
         SUMMARY OF THE INVENTION  
         [0009]    In a preferred embodiment of the present invention, a dual purpose carbonator/blending bottle, “blendonator”, is connected to a source of beverage syrup, a source of potable water and to a source of pressurized carbon dioxide gas. A pair of ratio valves provide for metering the water and syrup, which combined beverage then flow into a serpentine heat exchange coil and then into the blending bottle. Both he blending/carbonating bottle are retained within an ice bank cooled water bath tank. A refrigeration system provides for cooling an evaporator located in the water tank for forming the ice bank thereon. The blending bottle includes an outlet for connecting the interior volume of a freeze cylinder. The freeze cylinder also includes a further evaporator coiled around an exterior perimeter thereof. The freeze cylinder evaporator is connected to and cooled by the same refrigeration system that cools the evaporator in the water bath tank. A scraping mechanism within the cylinder provides for scraping frozen beverage from the inner surface of the cylinder. A control mechanism provides for controlling the refrigeration system and the cooling of both evaporators.  
           [0010]    In operation, the dual purpose blending bottle combines the functions of the separate carbonator and blending bottle system found in the prior art. Thus, the improved blender bottle serves both to carbonate the beverage and to retain a volume of a finished amount thereof. As it is located in the water bath tank, the volume of beverage therein is cooled by heat exchange transfer with the ice formed on the ice bank evaporator. A further volume of the beverage is retained in the serpentine coil and also maintained at a suitably cool temperature by heat exchange contact with the cooled water of the water bath. The beverage is therefore pre-cooled to a temperature just above its freezing point before delivery to the freeze cylinder. Thus, far less cooling power is needed to reduce the beverage to a frozen state, as would be the case in prior art FCB machines where the beverage is typically at a much higher ambient temperature just prior to its introduction into the freeze cylinder. Those of skill will understand that the ice bank provides for this extra cooling, which ice bank is formed by operation of the refrigeration system to build ice on the water bath evaporator. In the present invention, this added cooling is attained with a similar or even smaller sized refrigeration system components than would be used in comparable output prior art FCB machines. This enhanced cooling ability is obtained by the strategy of building an ice bank on the water bath evaporator ostensibly during times of non-dispense and/or when the freeze cylinder evaporator is otherwise not being cooled.  
           [0011]    A further advantage in the present invention is seen in the method of controlling the operation of the refrigeration system and the cooling of both evaporators thereof. The control system provides for directing refrigerant to either of the evaporators as is most efficient. Thus, if the FCB machine is in a “sleep” mode overnight when no drinks will be dispensed therefrom, the control can direct all the cooling ability if the refrigeration system be utilized to build up the ice bank at that time. Also, as is known in the art, when the beverage in the cylinder has reached its maximum desired viscosity, the cooling of the freeze cylinder evaporator must be stopped. Since a semi-frozen beverage can warm quickly to an unacceptably low viscosity the compressor must then be turned back on. However, and especially where the FCB machine has more than one freeze cylinder, the compressor can be turned on and off very frequently leading to damaging short cycling thereof. However, in the present invention, rather than stop the operation of the compressor, the control herein has an option to continue the operation of the compressor to cool the ice bank evaporator if further ice bank growth is needed or can otherwise be accommodated. Thus, when cylinder cooling is again required, refrigerant can again be directed thereto whereby a short cycling thereof can be avoided. This strategy of being able to alternate cooling between the cylinder evaporators and the ice bank evaporator presents a major advantage for compressor longevity, as most, if not all, short cycling can be avoided.  
           [0012]    A further advantage of the present invention concerns the ability of the electronic control system thereof to obtain more efficient cooling of the freeze cylinders. The present invention uses a control strategy that can more accurately maintain a pre-selected temperature differential between the inlet and outlet temperatures of the freeze cylinder evaporators. A control algorithm utilizes a proportional integral differential control approach that safely permits a much narrower temperature difference so that a greater length of each freeze cylinder evaporator can be utilized to cool the cylinder contents. Thus, the present invention, by being able to build a cooling reserve and by obtaining better cooling efficiency from the freeze cylinder evaporators, is able to accomplish more cooling with the same sized refrigeration system found in a comparable prior art machine or can accomplish the same amount of cooling with a smaller refrigeration system.  
           [0013]    In one preferred embodiment of the present invention, a freeze cylinder is used having a closed end and an open end. Around the cylinder adjacent the closed end a brushless DC stator is placed. The stator is connected to a DC power supply (or inverter). An evaporator is coiled around substantially the remainder of the exterior of the cylinder and connected to a mechanical refrigeration system. A spacer plate holds a bearing centrally thereof and is retained within the cylinder against the closed end thereof. A rotor is positioned in the cylinder adjacent the spacer plate. The rotor consists of metal ring around the perimeter of which are secured eight permanent magnets. The magnets are equidistantly spaced and alternate as to their polarity. The magnets and disk are encased in a food grade plastic creating a rotor disk having a central hole. A scraper extends along the axis of the cylinder and includes a central rod end that extends through the rotor and into the bearing of the spacer disk. The scraper includes a skirt portion around the rod end for securing to the rotor. The open end of the cylinder is sealed in the conventional manner with a plate which includes a valve for dispensing beverage from the interior volume of the cylinder and a rotational support for the opposite end of the scraper central rod. A delivery line provides for delivery of the beverage from a source thereof into the cylinder through a beverage inlet fitting.  
           [0014]    In operation, it can be understood that the stator and rotor constitute a brushless DC three phase motor that is operated by the power supply to rotate the scraper within the cylinder. Those of skill will readily appreciate that no dynamic seal is needed as no rod end of the scraper is required to extend out of the cylinder for mechanical connection to a drive motor. In addition, prior art machines require a gear case between the actual drive motor and the scraper rod. This mechanism is also eliminated by the present invention. Accordingly, the present invention provides for a machine that requires less in the way of service calls and that is thereby less expensive to operate. Encasing the rotor in a food grade plastic permits that portion of the motor to reside within the cylinder thereby making the motor an integral part of the cylinder.  
           [0015]    In a further embodiment of the present invention, a freeze cylinder is used that also has a closed end and an open end. A conventional motor and gear drive are used, however the gear drive is adapted to rotate a circular magnetic drive plate. The plate includes a plurality of permanent magnets of alternating polarity secured on one surface thereof in a circular arrangement. This external magnetic drive plate is positioned so that the magnetic surface thereof faces and is closely adjacent the exterior surface of the cylinder closed end. Within the cylinder a similar circular magnetic ring is rotatively mounted therein within an annular groove of a stainless steel disk. This internal disk is secured to a rod end of a scraper and the magnetic face of the magnetic ring faces the internal surface of the cylinder end and is positioned closely adjacent thereto. A round plastic collar is secured over the annular groove for sealing the magnetic ring therein.  
           [0016]    In operation, the motor is used to rotate the external magnetic drive plate. The external drive plate is magnetically coupled to the magnetic ring of the internal driven disk wherein rotation is imparted to the scraper. Thus, this embodiment of the present invention provides for a magnetic drive of the scraper wherein no dynamic seal is required. The internal magnetic ring is sealed from contact with the food product by the food compatible stainless steel and plastic collar, thereby permitting the use of that essential magnetic drive component within the cylinder.  
           [0017]    A method of making a condensation resistant stator is shown wherein the entire stator is first press fit into a stainless steel housing consisting of a rectangular face plate and a cylindrical sleeve which receives the stator. A first molding plug is then inserted into the center of the stator adjacent the face plate. A plastic material, such as a two part epoxy, is then poured to fill and cover a front half of the stator windings adjacent the face plate. A second central plug is then inserted into the upper half along with a pair of positioning pins, after which the rear half of the windings are similarly covered in plastic. Once the epoxy material has set, the central plugs can be removed. Those of skill will appreciate that the central plugs serve to keep the interior central surface of the stator free of plastic so that it can fit over the freeze cylinder with close direct contact there between. A plastic end plate is secured over the remaining open end of the housing for covering the stator. The housing and stator combination are subsequently attached to and around the closed end of the cylinder wherein the face plate enables such attachment thereof. An insulating material is then applied to cover the exterior surface of the stainless cylinder sleeve.  
           [0018]    It can be appreciated that as a result of the plastic encasing process, the windings of the stator are completely encapsulated and are thereby rendered essentially fully immune to any corrosive action of water condensation. The stainless housing further prevents access by water to the stator. In addition the plastic end plate and insulation covering the exterior of the stainless cylinder serve to further insulate the stator and prevent condensation from occurring thereon.  
           [0019]    A hole in the cylinder closed end wall extends through the center thereof, the perimeter of which is defined by an inward oriented perimeter flange. A pivot plug is retained in the central hole and welded thereto around the perimeter of the flange. A magnetic rotor is rotationally mounted within the cylinder wherein said plug extends through a central hole of the rotor. A scraper mechanism is secured to the rotor and is pivotally mounted on an opposite end thereof to a valve support plate covering the freeze cylinder open end. A beverage inlet line is fluidly secured to an inlet located on the cylinder end wall. In operation, the liquid beverage is delivered to the cylinder through the inlet line to the space created between the rotor and the inner surface of the cylinder end wall. The rotor includes a plurality of spokes through which the beverage fluid can flow into the main interior volume of the freeze cylinder to be formed into the semi-frozen food product. Thus, the fluid inlet through the cylinder end wall does not interfere with the evaporator and permits easier assembly and servicing.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0020]    A better and further understanding of the structure, function and the objects and advantages of the present invention can be had by reference to the following detailed description which refers to the following figures, wherein:  
         [0021]    [0021]FIG. 1 shows a perspective view of a frozen food product dispensing machine.  
         [0022]    [0022]FIG. 2 shows an exploded view of a frozen food product cylinder assembly in conjunction with a first drive mechanism of the present invention.  
         [0023]    [0023]FIG. 3 shows a plan view of the frozen food product cylinder assembly including the first drive mechanism of the present invention.  
         [0024]    [0024]FIG. 4 shows a cross-sectional view along lines  4 - 4  of FIG. 3.  
         [0025]    [0025]FIG. 5 shows a cross-sectional view along lines  5 - 5  of FIG. 2.  
         [0026]    [0026]FIG. 6 shows an electrical schematic for the first drive mechanism.  
         [0027]    [0027]FIG. 7 shows a cross-sectional view of a frozen food product cylinder assembly including a second drive mechanism of the present invention.  
         [0028]    [0028]FIG. 8 shows a surface plan view of a magnetic drive disk of the present invention.  
         [0029]    [0029]FIG. 9 shows a cross-sectional view along lines  9 - 9  of FIG. 7  
         [0030]    [0030]FIG. 10 shows a perspective view of a frozen food product dispensing machine.  
         [0031]    [0031]FIG. 11 shows an enlarged cross-sectional view of the driven disk.  
         [0032]    [0032]FIG. 12 shows a perspective view of the present invention.  
         [0033]    [0033]FIG. 13 shows a further perspective view of the present invention.  
         [0034]    [0034]FIG. 14 shows an perspective view of the present invention having the panels removed therefrom.  
         [0035]    [0035]FIG. 15 shows a partial cut away view of the water bath tank.  
         [0036]    [0036]FIG. 16 shows a cross-sectional plan view of a carbonator/blending bottle.  
         [0037]    [0037]FIG. 17 shows a top plan view of the a carbonator/blending bottle.  
         [0038]    [0038]FIG. 18 shows a schematic diagram of the refrigeration system.  
         [0039]    [0039]FIG. 19 shows a schematic diagram of the fluid beverage system.  
         [0040]    [0040]FIG. 20 shows a schematic diagram of the electronic control.  
         [0041]    [0041]FIG. 21 shows a perspective view of the dual ice bank control sensor.  
         [0042]    [0042]FIG. 22 shows a end plan view along lines  21 - 21  of FIG. 20.  
         [0043]    [0043]FIG. 23 shows a flow diagram of the viscosity monitoring control logic.  
         [0044]    [0044]FIG. 24 shows a flow diagram of the viscosity control logic  
         [0045]    [0045]FIG. 25 shows a flow diagram of the ice bank forming control logic.  
         [0046]    [0046]FIG. 26 shows a flow diagram of the expansion valve control logic  
         [0047]    [0047]FIG. 27 shows a partial plan cross-sectional view of a freeze cylinder assembly.  
         [0048]    [0048]FIG. 28 shows a partial perspective cross-sectional view of a freeze cylinder assembly.  
         [0049]    [0049]FIG. 29 shows a perspective view of a stator assembly.  
         [0050]    [0050]FIG. 30 shows an exploded view of a stator assembly.  
         [0051]    [0051]FIG. 31 shows a perspective view of a rotor of the present invention.  
         [0052]    [0052]FIG. 32 shows a plan view of the rotor of FIG. 31.  
         [0053]    [0053]FIG. 33 shows a cross-sectional plan view of the stator assembly with a lower molding plug therein.  
         [0054]    [0054]FIG. 34 shows a further cross-sectional plan view of the stator with both the lower molding plug and an upper plug therein.  
         [0055]    [0055]FIG. 35 shows a cross-sectional view of the stator assembly with the lower and upper molding plugs removed. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0056]    A frozen food product making and dispensing machine is seen in FIG. 1, and generally referred to by the number  10 . Machine  10  is illustrative of the type wherein the present invention can be applied. As seen by also referring to FIGS.  2 - 4 , a stainless steel cylinder  12  includes a cylindrical wall  14  and a stainless steel plate  16  welded to one end thereof forming a closed end surface and defining a cylinder interior  18 . A three phase stator  20  includes a ring portion  22  made of multiple lamination layers  22   a  to which three electrical windings  23  are wound and braided there around. Stator  20  is positioned on the end of cylinder  12  adjacent end wall  16  with cylinder wall  14  extending through the center thereof.  
         [0057]    A plastic spacer disk  24  is located within cylinder  12  and is positioned against end wall  16 . Disk  24  is made of a suitable food grade plastic and includes a bearing  26  mounted centrally thereof. As understood by also referring to FIG. 5, a rotor  30  includes a metal tube ring section  32  having eight permanent magnets  34  secured equidistantly around a perimeter thereof wherein the North and South polarities thereof alternate. Ring  32  and magnets  34  are encased in a food grade plastic  35 , such as Delrin®, molded there around and leaving a central shaft hole  36 .  
         [0058]    A scraper mechanism  40 , also made of a suitable food grade plastic, includes a central shaft  42  having a plurality of mixing rods  44  and scraper blade supports  46  extending therefrom. A pair of scraper blades  48  are mounted on supports  46  wherein holes  50  thereof receive pin portions  52  of supports  46 . Shaft end portion  54  extends through hole  36  and is received in hole  28  of bearing  26 . Shaft  42  also includes an attachment skirt  56  for securing thereof to rotor disk  30 . An opposite end  58  of shaft  42  is received in a short support section  60  integral with extending from a plastic end cover  62 . Cover  62  includes an o-ring  64  extending around a cylinder inserting portion  66  thereof. Cover  62  is secured to cylinder  12  by a plurality of bolts  67   a  and nuts  67   b . Flange  68 , as with plate  16 , is also made of stainless steel and welded to cylinder  12 . As is known in the art, cover  62  includes a hole  70  for receiving a dispensing valve  72 .  
         [0059]    As is understood by those of skill, an evaporator coil  74  extends around the exterior of cylinder  12  and includes an inlet fitting  74   a  and an outlet fitting  74   b . Fittings  74   a  and  74   b  are connected to high pressure line  76  and low pressure line  78  respectively of a mechanical refrigeration system including a compressor  80  and a condenser  82 . Insulation  84  extends around cylinder  12  and evaporator  14 . A beverage inlet line  86  is connected to a-cylinder inlet-fitting  88  and a beverage reservoir or mixing tank  90 . A pair of cylinders  12  can be secured within the housing of dispenser  10  and supported therein by a framework  92  thereof.  
         [0060]    As seen in the schematic of FIG. 6, a power supply  94  includes an inverter  96  for converting 220VAC to a three phase DC current. This three phase current is connected to the three winding  23  of stator  20 . Thus, those of skill will understand that stator  20  and rotor  30  comprise a DC motor. In operation, therefore, the three phase current induces movement of rotor  30  which, in turn, rotates scraper mechanism or assembly  40 . Thus, with a beverage, for example, delivered within cylinder  12  through line  86  and cooling thereof by evaporator  74  and its associated refrigeration system, frozen beverage can be produced by scraping thereof from the interior surface of cylinder  12 . The use of a rotor around which a food grade plastic has been molded permits that part of the DC drive motor to be internal of the cylinder and in contact with the food product. In general, all the components of the present invention are made of or coated with a suitable food grade material. Thus, the present invention comprises a drive mechanism for a frozen food product machine utilizing an internally scraped cylinder wherein the drive motor therefore is an integral part of the cylinder assembly. As a result, no dynamic seal or external shaft bearing is needed for the scraper mechanism. Thus, the traditional external motor, dynamic seal, external shaft bearing and transmission can be eliminated.  
         [0061]    In one example of the integral DC motor drive embodiment of the present invention, the drive motor is used in a cylinder that is approximately 15 inches long with a diameter of approximately 4.5 inches. The drive motor in such an application is designed to produce a torque of approximately 110 inch/lbs. at 100 RPM&#39;s.  
         [0062]    In a second embodiment of the present invention, as seen in FIGS.  7 - 9 , a cylinder  100  has a cylinder wall  102  and an end plate  104  defining a cylinder end surface  106 . An AC motor  108  is secured to a transmission  110  which is in turn secured to a plastic collar  112  attached to plate  104 . Transmission  110  includes a drive shaft  114  to which is attached a magnetic drive disk  116 . As seen in FIG. 8, disk  116  includes six permanent magnets  118  secured thereto around a perimeter of one side or face thereof wherein the north and south polarities thereof alternate. Magnets  118  are positioned to face and be held closely adjacent end surface  106 .  
         [0063]    Within cylinder  100  a food grade plastic spacer  120  is positioned against the interior surface of end wall  106 . Spacer  120  includes a central bearing  122  and includes an annular wall portion  124  defining a disk retaining space  126 . A food grade plastic collar  128  is received in stainless steel bearing  122  and on one end thereof has a driven magnetic disk  130  secured thereto. As seen by also referring to FIG., a stainless steel disk  130  includes a plurality of permanent magnets  131  arranged on a metal ring  132 . Ring  132  is secured to disk  130  within an annular groove  134  thereof as defined by walls  135 . A plastic collar or ring cover ring  136  is secured to walls  135  around a top perimeter thereof for sealably enclosing magnets  131  and ring  132  within annular groove  134 . Magnets  131  of disk  130  are positioned to face and lie closely adjacent the interior surface of end wall  106 .  
         [0064]    As with the first drive embodiment described above, the second drive embodiment also includes a scraper mechanism  40  having a central shaft  42  having a plurality of mixing rods  44  and scraper blade supports  46  extending therefrom. A pair of scraper blades  48  are mounted on supports  46  wherein holes  50  thereof receive pin portions  52  of supports  46 . A shaft end portion  140  is shaped as seen in FIG. 9, to provide for driving receiving thereof in a similarly shaped bore  142  of collar  128 . As with the previously described embodiment, an opposite end  144  of shaft  42  is received in support  60  extending from plastic end cover  62 . Flange  68 , as with plate  104 , is also made of stainless steel and welded to cylinder  100 .  
         [0065]    As with the previously described DC motor embodiment, cylinder  100  includes an evaporator coil  74  extending there around that includes an inlet fitting  74   a , an outlet fitting  74   b  and a food product/beverage inlet  88  for connection as stated above. Insulation  84  also extends around cylinder  100  and evaporator  74 . A pair of cylinders  100  can be secured within the housing of dispenser  10  and supported therein by a framework  92  thereof.  
         [0066]    In operation, motor  108  operates through transmission  110  to rotate magnetic disk  116 . Due to the magnetic coupling between disk  116  and  130  as they face each other on opposite sides of end wall  106 , rotation of disk  116  results in the rotation of disk  130 , and hence, rotation of scraper mechanism or assembly  40 . Thus, with beverage or food product delivered within cylinder  100  through line  86  and cooling thereof by evaporator  74  and its associated refrigeration system, frozen beverage can be produced by scraping thereof from the interior surface of cylinder  100 . This magnetic drive embodiment, as with the DC motor embodiment herein, eliminates the need for a dynamic seal and an external bearing with respect to the shaft  42  of the scraper mechanism  40 . Also, plate having an annular groove for receiving the magnets and ring wherein those components are sealed therein by a food grade plastic ring, permit the driven disk  130  to be in contact with food product, i.e. permits a magnetic drive approach or mechanism that is food compatible.  
         [0067]    A further embodiment of the present invention is seen in FIGS. 12 and 13 and generally referred to by the numeral  200 . Machine  200  has an outer housing having removable panels, including side panels  201 , a top panel  202  and a display door  203  having a transparency window  204 . Panels  201  and  202  include louvers  205  and an air flow grate  206 , respectively. A plurality of light fixtures  208  are secured door  203 , and are used for back lighting a transparency  210 . Door  203  is hinged to a front surface of machine  200 , and as seen in FIG. 13, can be swung to an open position for facilitating access to fixtures  208  and to user interface  212 .  
         [0068]    As seen by also referring to FIG. 14, machine  200  includes a framework  213  for supporting various internal components as well as the various portions of the exterior housing including housing panels  201  and  202 , and access door  203 . A pair of freeze cylinder assemblies  214  are held within separate insulated housings  216 . Both cylinder assemblies  214  are of the type disclosed above in FIGS.  2 - 6  herein and have DC drive motors  217  as also shown and described therein. However, unlike dispenser  10 , embodiment  200  includes a water bath tank  218 . Tank  218  includes sides  219  for retaining a volume of water therein. As seen by also referring to FIG. 15, tank  218  includes an ice bank forming evaporator  220 . Evaporator  220  is held therein by support means  222  and positioned thereby adjacent three of the four interior surfaces of sides  219 .  
         [0069]    A pair of specialized carbonator/blender bottles  224  are retained in tank  218 . Bottles  224  are seen in greater detail in FIGS. 16 and 17 and are essentially the same as the carbonator disclosed in co-pending U.S. patent application Ser. No. 08/761,191, filed Dec. 5, 1996, which application is incorporated herein by reference thereto. Bottles  224  each include a cylindrical stainless steel body  226  having a bottom end  228  and a top open end  230 . A plastic disk  232  is sized to fit within open end  230  and sealed there against by an o-ring  234 . Disk  232  is releasably retained in open end  230  by means of a wire spring or clip  238 . Clip  238  can be grasped by ends  238   a  thereof to remove from or insert into slots  240 , cut through cylinder  226 , through which radiussed corners  238   b  are inserted. Disk top surface  242  is designed to cooperate with clip  238  to minimize any accidental disengagement thereof with disk  232 . In addition, disk  232  includes a fluid inlet  244 , a gas inlet  246  for receiving pressurized carbon dioxide gas and a fluid outlet  248 . Disk  232  also includes a safety release pressure valve  250  and a liquid level sensor  252 . Sensor  252  includes a rod  254  that is positioned within bottle  224  having a movable float  256  free to slide there along. Rod  254  includes one or more magnetically actuated switches  258  therein and along the length thereof, and float  256  includes a magnet  260 . As is understood in the art sensor  252  operates whereby float  256  is carried by the level of liquid within  224 . As magnet  258  moves adjacent one of the switches  258  turning it on, then a level can be indicated. Inlet  244  is fluidly connected to a J-tube  262 , and outlet  248  is fluidly connected to a tube  264  extending to a point adjacent bottle end  228 .  
         [0070]    Water bath tank  218  also includes a two serpentine coils of heat exchange stainless steel tubing  262  positioned together and adjacent a fourth or remaining interior surface side against which evaporator  220  is not positioned. An agitator motor  264  is secured to a top cover panel  266  and includes a shaft and attached agitator blade, not shown, for agitating the water within bath  218 .  
         [0071]    As understood by also referring to FIG. 18, the refrigeration system used in machine  200  includes a refrigeration compressor  270  connected by refrigerant high pressure and low pressure lines  271   a  and  271   b , respectively, to a condenser  272 . Each cylinder assembly  214  includes an evaporator coil  274  and each evaporator coil has associated there with an electronically pulsed expansion valve  276  and a hot gas defrost valve  278 . Also, each coil  276  includes an inlet temperature sensor  277   a  and an outlet temperature sensor  277   b . The ice bank forming evaporator  220  is also connected to compressor  270  by high and low pressure lines  271   a  and  271   b . Evaporator  220  also has refrigerant metered therein by an electronically pulsed expansion valve  280 . Evaporator  220  also includes an inlet temperature sensor  282  and an outlet temperature sensor  284 .  
         [0072]    An ice bank  286  forms on evaporator  220  and, as further understood by referring to FIGS. 21 and 22, the size thereof is regulated by a pair of ice bank sensors  288   a  and  288   b . Sensors  288   a  and  288   b  each include a housing  290  wherein a pair of wire probes  291  extend. Probes  291  are connected to wires  292  that provide connection to the control of the present invention, further described below. Each housing  290  is secured to an attachment plate  293 . Sensor  288   a  is secured to a first level surface  293   a  of plate  293  and sensor  288   b  is secured to a second outer level surface  293   b  thereof. Thus, a differential distance D, as indicated by the dashed lines of FIG. 21, is created between the probes  291  of each of the sensors  288   a  and  288   b . A flange  294  and hook  295  provide for attachment of plate  293  to a suitable support means within ice bath  218  at a suitable distance from evaporator  220 .  
         [0073]    A schematic of the beverage fluid delivering system used in the present invention can be understood by referring to FIG. 19. A seen therein, an inlet water line  300  is connected to a source of potable water for delivering the water, first to a T-fitting  302  and then to a brixing or ratioing valve  304 . A second line  306  extends from fitting  302  to a float operated valve  308  positioned within water bath tank  218 . A third line  310  is connected to a source of beverage syrup, such as a bag-in-box  312 . Line  310  includes a fluid flow sensor  314  and is fluidly connected to a further brixing valve  316 . Sensor  314  is of the piston fluid contact type as, for example, model FS- 3 , as manufactured by Gems Sensors, of Plainville, Conn. Valves  304  and  316  provide for mixing the water and syrup at a ratio of typically 5 to 1 respectively. The fluid components flow to a Y-fitting  318  and are mixed together. A pump  320  pumps the properly ratioed, but as yet noncarbonated beverage, to a test valve  322  and from there to one of the heat exchange serpentine coils located in tank  218 . Valve  322  normally directs the beverage to a coil  262 , but can be manually operated to divert and deliver a test sample of the beverage along line  324  to an outlet point. In this manner the beverage can be easily tested to check for the proper ratioing thereof by valves  304  and  316 . The beverage flows from a coil  262  to inlet  244  of the associated blender/carbonator bottle  224 . A pressurized source of carbon dioxide gas  326  provides carbon dioxide first to a valve  328 . Valve  328  provides for diverting carbon dioxide gas to bag-in-box  312  in the example where a carbon dioxide pump  327  is used to move syrup therefrom. Those of skill will realize that other means, such as electric pumps can be used to pump the syrup whereby valve  328  would not be required. Or, carbon dioxide gas can be used to propel the syrup from a rigid stainless syrup tank. Regulator valves  330   a  and  330   b  provide the carbon dioxide at a desired pressure to the gas inlets  246  of each blender/carbonator  224  positioned in tank  218 . It will be appreciated that FIG. 18 shows a schematic of one of the beverage fluid systems, there being one for each assembly  214 .. Thus, in a machine  200  having two cylinders  214 , there are two brixing valves  304 , two brixing valves  316 , two coils  262 , tow pumps  320 , two flow sensors  314 , and two carbonator/blenders  224 . The outlets of each blender/carbonator  224  are connected to outlet lines  332  that are connected first to manual valves  234  and then to inlets  236  of each of the cylinders  214 . Valves  234  provide for manually stopping the flow of carbonated beverage to cylinders  214 , primarily for the purpose of facilitating servicing thereof.  
         [0074]    Sensors  314  provide a major advantage in that they are able to sense when the syrup has sun out whether the syrup is delivered from a bag-in-box or from a stainless tank. Prior art machines required that there be two sensor systems, one for either syrup containing source. A pressure sensor was required for the bag-in-box as, when the bag became empty, there would be no pressure, and that would indicate a sold out condition. However, if a tank was used the carbon dioxide gas used to propel the syrup would indicate to the pressure sensor that syrup was present, when in fact, it was not. Thus, a tank syrup reservoir required a float sensor that would only be affected by actual liquid syrup. Therefore, sensor  314  eliminates having redundant systems and the associated cost and complexity thereof.  
         [0075]    It can be appreciated that the present invention provides for the cooling of a volume of beverage within coils  262  prior to introduction thereof into each blender/carbonator  224 . Thus, the beverage will have reached a temperature of approximately 36 degrees Fahrenheit prior to the introduction thereof into a corresponding container  224 . In addition, each blender/carbonator is also held at the same temperature being immersed in the cold water bath. Therefore, the carbonation of the beverage that occurs therein can reach a desired level of saturation at much lower carbon dioxide gas pressures than if the mixing were occurring in a bottle held at a much warmer room ambient temperature. In addition, the present invention has a much greater beverage production capacity, as an ice bank presents a large cooling reserve that would otherwise not be available unless an exceedingly large refrigeration system is used. Thus, as the beverage is presented to the freeze cylinder at a very low temperature, the cooling required of the freeze cylinder evaporators is much lower so that overall, the present invention works much more efficiently than do comparable prior art machines that produce semi-frozen beverages or food products from beverage delivered to the cylinders at ambient temperatures.  
         [0076]    As seen in FIG. 20, the present invention uses a distributed electronic control having a product delivery control board  340  for the control of each cylinder  214 . A main logic board  342  is connected to each control board  340 , and there is one inverter board  344  for each of the two cylinders  214 . The boards communicate as is generally indicated by the arrows of FIG. 19. Main board  342  receives inputs from the user interface  212 , and from each of the product delivery board ( 340 ) on the system, as well from the CO 2  pressure sensor, an H 2 O pressure sensor, high/low line voltage, ice bank thickness (min), ice bank thickness (max.), ice bank evaporator input temperature and ice bank evaporator output temperature. Main board  342  controls the operation of compressor  27 —on/off, ice bank agitator motor and ice bank pulse valve. Each product delivery board receives inputs from its associated syrup flow sensor  314 , level sensor  252 , evaporator input temperature sensor, evaporator output temperture sensor, product viscosity sensor and beater motor error, and controls the operation of its associated beater motor on/off, defrost valve on/off, pulse valve on/off, syrup valve on/off, H 2 O valve on/off, disp. Valve lockout, product status light and blendonator pump  320 . The inverter board  344  provides for inverting the 240VAC supplied current to the 340VDC current used by motors  217 . In addition, it senses the current draw being placed on each motor  217  and runs them at a constant  120  revolutions per minute (RPM).  
         [0077]    A distributed control is used to better accommodate machines having more than two cylinders  214 . Thus, the main board  342  can be designed to work with more than two product delivery boards. In this manner, a cost saving can be had as opposed to having a main control board having to be designed specifically for each machine having a particular number of cylinders. The main board receives the commands from the operator interface, and distributes this information to the appropriate board. For instance, if the operator wants to turn on cylinder # 1 , the main board will send the “on” command to the product delivery board on cylinder # 1 . The PDB will then tell the inverter board to apply power to stator # 1 , as well as request the compressor to come on and begin pulsing the pulse valve for cylinder # 1 .  
         [0078]    A better understanding of the control logic utilized by the control of the present invention to monitor the viscosity of the beverage, control the viscosity of the beverage and to regulate the ice bank can be had by referring to the flow diagrams thereof shown in FIGS.  23 - 26 . Viscosity is monitored as a function of the current draw of the DC drive motor for the particular cylinder. In addition, each motor  217 , as stated above, is controlled to operate at a constant 120 RPM rate. Thus, the more viscous the beverage the greater load and current draw on the motor  217  to maintain the set point rotational speed. Since the motors  217  are directly driving the cylinder scraper mechanisms, and the RPM&#39;s are kept constant, there exists a very direct correlation between the current draw of the motors and the viscosity of the food product. Each product delivery board has look up tables that correlate the current draw to an arbitrary viscosity number scale, which scale is utilized by each board to indicate a level of viscosity of the beverage within the cylinder. As seen in FIG. 23, a start point is indicated by block  350 . The viscosity is monitored by each board  340 ,wherein at block  351  it is determined if the viscosity is below a preset viscosity minimum. If the viscosity is below that minimum, and it has been below that minimum for greater than one second, block  352 , then at block  354 , it is determined if compressor  270  is on. If compressor  270  is on, then the viscosity is controlled at block  356 . A more detailed description of the viscosity control is contained below with reference to FIG. 24. If compressor  270  is not on, then the control inquires if it has been off for more than two minutes, block  358 . If it has, then compressor  270  is turned on at block  360  and viscosity is controlled at block  356 . At block  361 , it is determined if the desired viscosity has attained a predetermined desired level. If it has, the compressor is turned off at block  362  and the control goes to return at block  364  and monitors the viscosity. If at blocks  351 ,  352  or  358  it is determined, respectively, that the viscosity is not below viscosity minimum or the viscosity minimum was not maintained for more than one second or that the compressor has been off for less than two minutes, then the control, at block  366 , determines if the float sensor  252  of the associated bottle  224  has been activated to signal for more beverage to be pumped therein, i.e. has beverage been drawn from the associated cylinder whereby further beverage must be replaced therein, and in its associated carbonator/blender  224 . If the float has been activated, then further beverage is added to the cylinder by control of pump  320  and operation of valves  304  and  316 . The control then inquires, at block  368 , if the compressor is on, and turns the compressor on as needed or proceed directly to viscosity control, block  356 . If the sensor  252  has not been activated to deliver more beverage within its associated bottle  224 , block  366 , then the control determines if 5 minutes has elapsed since the last refrigeration cycle, block  370 . If less than the 5 minutes has elapsed, the control goes to return, block  372  where viscosity is monitored. If more than 5 minutes have elapsed since the last operation of the compressor, the control then inquires, at block  368 , if the compressor is on, and turns the compressor on as needed, block  360 , or proceeds directly to viscosity control, block  356 .  
         [0079]    The viscosity control of the present invention can be better understood in terms of the flow diagram of FIG. 24. At the start block  380  the control moves to blocks  381  and  382 , where the board determines the inlet and outlet temperatures, respectively, of the particular evaporator coil  274 , and at block  384 , measures the barrel viscosity. At block  386  it is determined if the viscosity is greater than a pre-selected viscosity maximum. If it is, the control queries if the particular coil  274  is in the “top off mode”, block  388 . If not, the top off mode is begun at block  390 . The top off mode is a sequence that permits a relatively accurate determination of the beverage viscosity. Thus, at block  392  a 3 second timer is started during which the associated pulse valve  276  is closed, block  393 . Further refrigeration is stopped for this time period, however the scraper mechanism continues to turn. At block  394  pulse valve  280  is operated to provide for building of the ice bank. A further understanding of the control of the ice bank will be had below in reference to FIG. 25. At block  396 , the maximum viscosity sensed during the top off period is recorded. If the 3 second timer has timed out, block  398 , then the control determines if the difference between the present viscosity and the maximum viscosity currently sensed during top off is lesser or greater than a pre-selected viscosity delta or difference, block  400 . The delta is contained in a look-up table and is an experimentally derived number. If the delta is not exceeded, this means that the viscosity of the beverage is at the desired level and refrigeration of the cylinder can be stopped, block  402 , and the control can go to return  404 . If the measured delta is too large, i.e. in excess of the preset delta, this indicates that the beverage is not viscous enough. Then the control goes to block  406  ending top off and continuing refrigeration and goes to return  404 . Ice can not be built on evaporator  220  during refrigeration of either coil  274 . Only when both cylinders are satisfied and/or are otherwise not being cooled. Thus, if the other cylinder evaporator  274  is being cooled, cooling of evaporator  220  is not permitted. Therefore, ice can be formed during top off if the other coil  274  is not being cooled or if both are in top off. As a consequence thereof, if top off has ended as the delta was too large, block  400 , further cylinder cooling is required and cooling of evaporator  220  is stopped, if one or both cylinders  214  are in a refrigeration sequence. At block  386 , if the viscosity is below the preset viscosity maximum, then at block  408  the temperature of the particular inlet of the associated coil  274 , as measured by sensor  277   a , is determined. If that temperture is greater than 40 degrees Fahrenheit, then a proportional/integral/differential “PID” calculation is made to control the temperature down to 40° F., block  410 . As is understood in the control art, PID control generally follows the equation PID=E c (K p )+(E p1 , E p2  . . . E c )K i +((d)E/(d)t)K d . where Ec is the current error, K p  is a proportional proportionality constant, E p1  . . . represent previous error values, K i  is the integral proportionality constant, (d)E/(d)t is the rate of change of the error and K d  is the associated differential proportionality constant. The value (E p1 , E p2  . . . E c ) represents an equation, such as the averaging of the E values, that, multiplied by K i  represents the portion of the PID valve that is based on the size the error over time. The E c (K p ) value represents the portion of the PID valve that is based on the size of the currently measured error. All three variables can be used produce a very accurate understanding of how a particular target point is being approached. In the present invention, PID control is used to control to a 40 degree F. set point with a high degree of accuracy. The particular pulse valve  276  is operated accordingly, block  412 , as per the PID output. If at block  408  the temperature of the inlet is less than 40 degrees F., then it is determined if the outlet temperature, as determined by sensor  277   b , is greater than 46 degrees F., block  414 . If that temperature is greater than 46 degree F., then the logic control returns to blocks  410  and  412  and controls the temperature of the inlet to 40 degrees F. Thus, the control is first seeking to establish a delta T of six degrees between the coil  274  inlet and outlet temperatures at a particular starting point where the inlet temperature is 40 degree F. and an outlet temperature is 46 degrees. When that is accomplished, then, at block  416 , the PID control can be used to simply control the delta T to 6 degrees F. whereby the inlet and outlet temperatures can fall below 40 and 46 respectively, as long as the delta T of 6 degrees between them is accurately maintained.  
         [0080]    A better understanding of the ice bank control herein can be has with reference to FIG. 25. At the start point  420 , the control then starts a 30 second ice measure timer, block  421 . During that 30 second interval ice sensors  288   b  and  288   a  are measured, respectively, blocks  422  and  423 . After the 30 second timer has timed out, block  424 , the control determines if either cylinder  214  is calling for refrigeration, block  425 . If either cylinder is calling for refrigeration then it is determined if the compressor  270  is running, block  426 . The compressor is then turned on, block  427 , or the control goes directly to block  428 . At block  428  it is determined if either cylinder is in a normal operate mode, i.e. not in top off and requiring refrigeration. If either cylinder is in a normal operating mode, then no refrigeration of the ice bank can occur and the control goes to return, block  429 . If one or both are not in normal mode, i.e. in top off mode, then the particular pulse valve  276  is pulsed at the top off rate, block  430  and the control goes to return  431  the rate that is determined to maintain a 20 degree F. temp. If, at block  425 , neither cylinder  214  is calling for refrigeration, then ice bank sensor  288   b  is polled to determine if ice is present, block  432 . If sensor  288   b  senses ice, then no more building of ice is desirable so, if the compressor is running, block  434 , it is turned off, block  435  and valve  280  is opened for 5 seconds to equalize pressure, block  436 , and the control goes to return,  438 . If sensor  288   b  does not sense ice, then at block  440 , the control looks at sensor  288   a  to see if it senses ice. If sensor  288   a  so indicates, then the control follows blocks  434 ,  435 ,  436  and  438 . If sensor  288   a  does not sense ice, then ice can and should be added to the ice bank, it having eroded to a point that a greater cooling reserve is desirable. Thus, at block  444 , if the compressor is running, pulse valve  280  is operated to cool evaporator  220  and build ice thereon, block  445 . If the compressor is not running, it is turned on, block  446 . Pulse valve  280  is operated as per the flow diagram valve control loop delineated in FIG. 26 below.  
         [0081]    As can be understood by referring to FIG. 26, at a start point  450 , the control measures evaporator  220  inlet temperature using sensor  282   a , block  452  and then measures the outlet temperature thereof using outlet sensor  282   b , block  454 . The delta T of evaporator  220  is controlled in substantially the same manner as previously described for the cylinders  214 . Thus, the inlet temperature is first sensed, block  456 , and moved down using a PID control, block  458 , and a valve pulse timer as per that PID calculation, block  460 , to a preset temperature of 20 degrees F. Once that value is attained, the control goes to return, block  462 . If the inlet temperature is less than 20, then the control determines if the outlet temperature is greater than 40 degrees, block  464 . If it is then the control returns to blocks  458  and  460  to move the inlet temperature to 20 degrees F. Once the inlet temperature is equal to 20 degrees F. and the outlet temperature is equal to −40 degrees F., then at block  464 , the control then moves to block  466 . At block  466  a PID control is utilized to maintain a delta T of 20 degrees F. The pulse valve  280  is set accordingly, block  468 , and the control goes to return, block  270 .  
         [0082]    Those of skill will understand that the present invention provides for the production of a semi-frozen food product in a manner that maximizes the efficiency of operation of the refrigeration system thereof. The life of the compressor is extended as refrigerant gas can be alternately directed to either of the cylinder evaporators  274  or the ice bank evaporator  220 . In particular, the two ice bank sensors provide for an incremental area between an ice bank maximum size and an ice bank minimum size where the ice bank can be grown to prevent the compressor from running and building pressure after both the valves  276  are closed. In this manner the compressor is not short cycled or presented with damaging high pressures when an expansion valve is closed. Since the erosion of the ice bank generally occurs at a faster rate than it is built up, it is contemplated that there will be very few or no occasions where the refrigerant can not be diverted to evaporator  220  so as to protect the compressor.  
         [0083]    Furthermore, as an ice bank is used, a large cooling reserve can be built up during the times that neither cylinder  214  is calling for refrigeration, such as when the beverage therein is of sufficient viscosity, or where the cylinders have been shut down entirely during a “sleep mode”, well known in the art, where no drinks will be dispensed. Also, as the PID control permits a much smaller delta T to be maintained in a safe manner, better efficiency of cooling is obtained from evaporators  274  and evaporator  220 .  
         [0084]    Dispenser  200  therefore has a substantial advantage over comparable prior art machines in terms of refrigeration system design parameters. Dispenser  200  can use a much smaller compressor to do the work of a larger compressor in a prior art machine, or obtain more cooling from the same sized system.  
         [0085]    As seen by again referring to FIG. 3, framework  213  defines three areas  500 ,  502  and  504 . Top area  500  will be understood to retain water bath  218 , condenser  272  and compressor  270 . Middle area  502  retains cylinder packs  216 , and the expansion valves  276  and  280  and the defrost valves  278 . Lower section  504  includes beverage pumps  320  and ratio valves  304  and  316 . As is known in the art, defrost valves  278  serve to provide hot gas defrost of each cylinder  214 . Such defrost is periodically required to remove large particles of ice that can periodically form within a cylinder. A filter grate, not shown, is secured to condenser  272  on the exterior side of beverage machine  200  opposite from the fan  273  thereof.  
         [0086]    Enlarged cross-sectional views of improved freeze cylinder assemblies  508  are seen by referring to FIGS. 27 and 28. Insulation  510  is located within housing  511  for insulating evaporator  274 . In the preferred form of the drive motor of the present invention, there is included an improved stator  512  and rotor  514 . As seen by also referring to FIGS. 29 and 30, stator  512  includes a metallic inner ring  513  and a plastic  515  encases the windings  516  thereof. Methods for providing for such plastic molding of stator  512  are described in greater detail herein below. Stator  512  is press-fit within a stainless steel cylinder  518  and a stainless end plate  520  is secured to one end of cylinder  518 . Plate  520  includes a central hole  520   a  and four mounting holes  520   b . A pair of centering tabs  521  extend through plate  520  and out of the opposite end of cylinder  518 . A molded plastic end cover  522  defines an outer face surface  523  and recess area  524 , and is retained over and covering the end of cylinder  518  opposite from plate  520 . Cover surface  523  includes a hole  525  through which wire connector  526  extends for providing electrical connection to stator  512 . A central hole  528   a  and a beverage inlet fitting hole  528   b  extend through cover end surface  529 . A beverage inlet fitting  530  is secured to end wall  532  of a freeze cylinder  533 . A syrup delivery line  534  is connected to fitting  530  and is, in turn, connected to a source of liquid beverage, as described herein above.  
         [0087]    A pivot pin  536  is secured to end wall  532  and provides for the rotational support of rotor  514  thereon. As seen in FIGS. 31 and 32, rotor  514  includes a molded outer plastic shell  538  and has an annular groove  540  on either side thereof defining a thin floor or web portion  342  through which extend three syrup flow openings  544 . A scraper drive key  546  extends from rotor  514  and is inserted within a slot  548  of a scraper  550 . It can be appreciated that a fully assembled stator housing, generally designated by the numeral  552 , as seen in FIG. 31, is secured to cylinder housing  511  by four bolts extending therefrom, not shown, that extend through holes  519  to which threaded nuts are then secured. Cover  522  is secured by a bolt  554  extending through hole  528   a  and threaded into pin  536 . A water proof insulating material  538  is wrapped around the exterior of cylinder  518  and also retained within recess  524 .  
         [0088]    In operation, it can be understood that rotation of rotor  514  by three phase current flow through stator  514 , as described above, causes rotation of rotor  514 , hence rotation of scraper  550 . Beverage is delivered to cylinder  533  through line  534  and inlet  530  to a space between rotor  514  and end wall  532 . The beverage can then flow through rotor  514  through the openings  544  and into cylinder  533  for production of the slush beverage. It can be appreciated that entering the beverage from the cylinder end wall  532  is preferable to entering through the cylinder wall itself, as such would conflict with the evaporator  274 . Thus, the maximum surface area of cylinder  533  can be in contact with and covered by evaporator  274  to optimize the cooling thereof.  
         [0089]    A method for forming plastic encased stator  514  can be understood by referring to FIGS.  33 - 35 . As seen in FIG. 33, high density plastic plug  560  is inserted into stator assembly  552  through hole  518   a  of plate  518 . Plug  560  includes a convex conical end surface  562 , a central overflow channel  563 , and extends approximately halfway through the center of stator  512 . A flowable plastic material, such as, a two part epoxy, is mixed and poured into the space S between windings  516  and cylinder  518  to form encasing plastic  515 . The plastic material is first filled to a level indicated by point L 1  just below a lowest point of conical surface  562 . After that material has hardened, a second plug  564  is inserted in the opposite end of assembly  552 . It will be appreciated that assembly  552 , as seen in FIG. 34, does not at this point include cover  522 . Plug  564  includes a slightly smaller diameter inner portion  564   a  and a slightly larger diameter outer portion  564   b . Plug  564  also includes a concave conical surface  566  and a central recess  568 . Conical surface  566  exists at a slightly steeper or greater angle than that of surface  562 . A plastic ring  570  extends around plug outer plug portion  564   b  and includes a radiused surface  572 . After plug  564  with ring  570  are in place, further plastic material is poured into and fills space S to a level L 2 . It can be appreciated that any excess plastic material can flow in the space created between the conical surfaces  562  and  566  resulting from their differing angles, and down and out of central bore  563 . After the plastic material has hardened, plugs  560  and  564  are removed. It can be appreciated that plugs  560  and  564  have central diameters very close to that of the center of stator  512  so that not material P is permitted to flow and harden thereon. Ring  570  provides for a radiused edge to permit better cooperative fitting with cover  522 . By encasing windings  516  in plastic, they are rendered substantially immune to the corrosive effects of water and other corrosive chemical agents alone or in combination.