Abstract:
A cryogenic processor is provided for liquid feed preparation of a free-flowing frozen product comprising. In accordance with one aspect of the invention, the cryogenic processor includes a freezing chamber having a substantially conical shape, at least one feed tray overlying the freezing chamber arranged and adapted to receive liquid composition from a delivery source, the tray having a plurality of orifices for the discharge of uniformly sized droplets of the composition from the feed tray, whereby the droplets are delivered by gravity into the freezing chamber there-below. The cryogenic processor also includes at least one sensor associated with the feed tray for determining a depth of liquid composition in the feed tray, at least one valve associated with a liquid composition delivery line, the valve being configured to control the rate at which liquid composition is delivered from the delivery source to the feed tray, and a controller responsive to the at least one sensor for controlling a position of the valve, and therefore the rate at which liquid composition is delivered from the delivery source to the feed tray.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/617,724, filed Jul. 17, 2000, now U.S. Pat. No. 6,209,329, which is a continuation-in-part of U.S. patent application Ser. No. 09/451,046, filed Nov. 30, 1999, now U.S. Pat. No. 6,223,542, which is a continuation of U.S. patent application Ser. No. 09/066,140 (now U.S. Pat. No. 6,000,229), filed on Apr. 24, 1998, both entitled “Cryogenic Processor for Liquid Feed Preparation of a Free-Flowing Frozen Product and Method for Freezing Liquid Composition.” Each of these prior applications are hereby incorporated by reference in their entireties. This application also claims the benefit of U.S. provisional application serial No. 60/232,564, filed Sep. 14, 2000. 
    
    
     MICROFICHE APPENDIX 
     This specification includes a microfiche appendix in compliance with 37 C.F.R. §1.96(c) consisting of two (2) slides and 166 frames. 
     1. Field of the Invention 
     The present invention relates generally to a frozen product preparation apparatus and, more particularly, to a cryogenic processor for liquid feed preparation of a free-flowing frozen product. 
     2. Description of the Prior Art 
     Sales of ice cream and frozen yogurt products have risen dramatically in recent years, and applicants herein have captured a portion of this product market through the development of a unique novelty ice cream, frozen yogurt and ice product in the form of beads. This product, marketed under the trademarks “Dippin&#39; Dots®” and “Ice Cream of the Future®”, has become very popular in specialty stores, at fairs and theme parks, and through vending machines. 
     Applicants have proprietary rights in the method of preparing and storing the product pursuant to U.S. Pat. No. 5,126,156, issued Jun. 30, 1992, herein incorporated by reference, as well as rights associated with improvements pursuant to U.S. Pat. No. 5,664,422, issued Sep. 9, 1997, and U.S. Pat. No. 6,000,229, issued Dec. 14, 1999, herein incorporated by reference. As is generally described therein, the patented method involves delivering flavored liquid dairy and other alimentary compositions to a feed tray and then dripping the composition into a freezing chamber. The feed tray comprises a plurality of orifices through which liquid composition passes to fall into the freezing chamber, either in the form of droplets or liquid streams, which streams break into droplets before freezing. Each orifice may also have a corresponding feed dropper, which is downwardly disposed in relation to the tray such that the liquid composition passes from the tray through an orifice and then through an associated feed dropper where a droplet or liquid stream is formed. The orifices or combination of orifices and feed droppers will hereinafter be referred to collectively as feed assemblies. 
     The falling droplets of liquid composition freeze rapidly (i.e., flash freeze) in the freezing chamber due to the presence of both gaseous and liquid refrigerant in the area between the orifices and the bottom of the freezing chamber, thereby forming solid beads of flavored ice cream, yogurt or other alimentary products, such as flavored ice. More specifically, as droplets of liquid free fall through a gaseous region of the freezing chamber, and before the droplets contact the liquid refrigerant, the outer spheres of the droplets form a thin frozen shell. This thin frozen shell serves to protect the spherical shape of the droplets as they impact the surface of the liquid refrigerant. The remainder of the droplets freeze completely as they pass through the liquid refrigerant, and before reaching the bottom of the freezing chamber. The frozen beads are removed from the freezing chamber and packed for distribution and later consumption. 
     It should be appreciated that the cryogenic processor used for preparing the above-described beaded ice-cream is a relatively sophisticated apparatus that should be tightly controlled for proper operation. For example, the liquid refrigerant preferably used is liquid nitrogen, which has an extremely high evaporation rate. It is typically desired to maintain approximately 19-21 inches of separation between the surface of the liquid nitrogen and the feed tray. If this separation distance is too small, then the liquid droplets may not have sufficient time during their free-fall from the feed tray to form the desired spherical shape. If the separation distance is too large then the impact of the droplets with the surface of the liquid nitrogen may become undesirably large. Accordingly, the introduction of liquid nitrogen into the freezing chamber should be closely controlled. 
     In addition, the rate at which liquid composition passes through the orifices of the feed tray and the size of the droplets is controlled by the level of liquid composition maintained in the feed tray. As a result, the delivery of the liquid composition to the feed tray should be tightly monitored and controlled. 
     In addition to the desire to closely control operation parameters of the cryogenic processor, other improvements are desired. For example, it is often desired to manufacture beaded ice-cream of various flavors. Often, unique flavors are created by mixing certain fundamental or base flavors. One way this may be accomplished is by manufacturing a first base flavor, then manufacturing a second base flavor, then mixing the two beaded ice-cream products. This approach, however, requires that piping and other machinery be cleaned between “batches” (i e., flavor changes). Another disadvantage of this approach is the added step of mixing the beaded form of the two base flavors. 
     Another way that a multi-flavor product may be created is by mixing the liquid form of the base flavors in appropriate proportions, before delivery to the feed tray. This approach, however, also requires that piping and other machinery be cleaned between batches. 
     Accordingly, it is desired to provide an improved cryogenic processor for preparing a unique, beaded ice-cream product. 
     SUMMARY OF THE INVENTION 
     Certain objects, advantages and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     To achieve the advantages and novel features, the present invention is generally directed to a cryogenic processor for liquid feed preparation of a free-flowing frozen product comprising. In accordance with one aspect of the invention, the cryogenic processor includes a freezing chamber having a substantially conical shape, at least one feed tray overlying the freezing chamber arranged and adapted to receive liquid composition from a delivery source, the tray having a plurality of orifices for the discharge of uniformly sized droplets of the composition from the feed tray, whereby the droplets are delivered by gravity into the freezing chamber there-below. The cryogenic processor also includes at least one sensor associated with the feed tray for determining a depth of liquid composition in the feed tray, at least one valve associated with a liquid composition delivery line, the valve being configured to control the rate at which liquid composition is delivered from the delivery source to the feed tray, and a controller responsive to the at least one sensor for controlling a position of the valve, and therefore the rate at which liquid composition is delivered from the delivery source to the feed tray. 
     In accordance with another aspect of the invention, a method is provided for feeding liquid composition to a freezing chamber containing a refrigerant to form beads of frozen product. In accordance with this aspect of the invention, the method monitoring a level of liquid composition in each section of a multi-partition feed tray, closely controlling the delivery a liquid feed composition from a source to each section of the feed tray, discharging the liquid feed composition from each section of the feed tray through orifices in the form of droplets, via gravity, into a freezing chamber disposed below the orifices, monitoring a level of liquid refrigerant in a freezing chamber, and closely controlling the delivery of liquid refrigerant to the freezing chamber, in response to the step of monitoring the level of liquid refrigerant. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. In the drawings: 
     FIG. 1 is a cross-sectional elevation of the improved cryogenic processor. 
     FIG. 2 is a cut-away perspective view of the adjustable air inlet doors. 
     FIG. 3 is a cross-sectional elevation of an improved cryogenic processor, similar to FIG. 1, but further illustrating motorized control of air inlet doors. 
     FIG. 4 is a diagram of the improved cryogenic processor illustrating various control sensors and valves. 
     FIG. 5 is a top-view of a multi-partition feed tray used in one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Having summarized various aspects of the present invention, reference will now be made in detail to the description of the invention as illustrated in the drawings. While the invention will be described in connection with these drawings, there is no intent to limit it to the embodiment or embodiments disclosed therein. On the contrary, the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention as defined by the appended claims. 
     Reference is now made to FIG. 1 showing an improved cryogenic processor constructed in accordance with the preferred embodiment of the present invention to produce free-flowing frozen product in the form of small beads. The fundamental method utilized to produce the product is described in detail in U.S. Pat. No. 5,126,156, and will be summarized below in order to facilitate an understanding of this unique production process. The apparatus as depicted in FIG. 1 enhances the efficiency of the prior art production process and increases product yield as described below. 
     Cryogenic processor  10  includes a freezing chamber  12  that is most preferably in the form of a conical tank that holds a liquid refrigerant therein. Freezing chamber  12  incorporates an inner shell  14  and an outer shell  16 . Insulation  18  is disposed between the inner shell  14  and outer shell  16  in order to increase the thermal efficiency of the chamber  12 . The freezing chamber  12 , as shown in FIG. 1, is a free-standing unit supported by legs  22 . Alternatively, the freezing chamber  12  may be disposed in a frame that is specially built to support the processor  10  while in use. 
     Refrigerant  24 , preferably liquid nitrogen in view of its known freezing capabilities, enters the freezing chamber  12  by means of refrigerant inlet  26 . Refrigerant  24  entering chamber  12  through inlet  26  is used to maintain a predetermined level of liquid refrigerant in the freezing chamber and must be added to replace refrigerant  24  that is lost by evaporation or by other means incidental to production. Gaseous refrigerant that has evaporated from the surface of the liquid refrigerant  24  in freezing chamber  12  primarily vents to the atmosphere through exit port  29  which cooperates with the vacuum assembly  30 , which can be in the form of a venturi nozzle. Extraction of the frozen beads occurs through product outlet  32  adapted at the base of the freezing chamber  12 . 
     When incoming refrigerant  24  enters the freezing chamber  12  through inlet  26 , a swirling or cyclonic motion of refrigerant  24  may form in the freezing chamber  12  depending on the amount of refrigerant  24  allowed to enter through inlet  26  and the flow velocity of the incoming refrigerant  24 . This cyclonic motion is not favorable to the production process because the frozen beads awaiting extraction at the bottom of freezing chamber  12  may be swept into the swirling refrigerant and thus prevented them from falling to the bottom of the freezing chamber for collection. A non-uniform beaded product can also be produced in this turbulent environment. This unwanted cyclonic motion of the incoming refrigerant is prevented by baffles  34  mounted to interior surface  36  of inner shell  14 . Baffles  34  extend inwardly from interior surface  36  in the vicinity of the refrigerant inlet  26 . Additionally, the baffles  34  are oriented so that their lengths are substantially vertical within the freezing chamber  12 . 
     An ambient air inlet port  28  with adjustment doors  38  and exit port  29  with adjustment doors  39  are provided to adjust the level of gaseous refrigerant which evaporates from the surface of the liquid refrigerant  24  so that excessive pressure is not built up within the processor  10  and freezing of the liquid composition in the feed assembly  40  does not occur. 
     A feed tray  48  receives liquid composition from a delivery source  50 . Typically, a pump (not shown) drives the liquid composition through a delivery tube  52  into the feed tray  48 . A premixing device  54  allows several compositions, not all of which must be liquid, such as powdered flavorings or other additives of a size small enough not to cause clogging in the feed assembly  40 , to be mixed in predetermined concentrations for delivery to the feed tray  48 . 
     It is recognized that in order to create uniformly sized beads  56  of frozen product, uniformly sized droplets  58  of liquid composition are required to be fed through gas diffusion chamber  46  to freezing chamber  12 . The feed tray  48  is designed with feed assembly  40  that forms droplets  58  of the desired character. The frozen product takes the form of beads that are formed when the droplets  58  of liquid composition contact the refrigerant vapor in the gas diffusion chamber  46 , and subsequently the liquid refrigerant  24  in the freezing chamber  12 . After the beads  56  are formed, they fall to the bottom of chamber  12 . A transport system connects to the bottom of chamber  12  at outlet  32  to carry the beads  56  to a packaging and distribution network for later delivery and consumption. 
     In accordance with one aspect of the invention, the preferred embodiment is designed with an incorporated vacuum assembly  30  which can take the form of a venturi. The vacuum assembly  30  cooperates with air inlet  28  and adjustment doors  38  so that an ambient air-flow passes through the inlet  28  and around feed assembly  40  to ensure that no liquid composition freezes therein. This is accomplished by mounting the vacuum assembly  30  and air inlet  28  on opposing sides of the gas diffusion chamber  46  such that the incoming ambient air drawn by the vacuum assembly  30  is aligned with the feed assembly. In this configuration, ambient air flows around the feed assembly warming it to a sufficient temperature to inhibit the formation of frozen liquid composition in the feed assembly flow channels. Air source  60 , typically in the form of an air compressor, is attached to vacuum assembly  30  to provide appropriate suction to create the ambient air flow required. 
     As mentioned above, air inlet  28  incorporates adjustment doors  38  for controlling the amount of incoming ambient air. As shown in FIG. 2, the preferred embodiment of the doors  38  is a series of slidable door segments  62  mounted within a frame  64 . This configuration accommodates numerous adjustment combinations so that the desired flow rates may be achieved between a full open setting where the doors  38  expose a maximum size inlet opening and a full closed setting where the doors completely block the inlet  28 , thereby preventing ambient air flow. It should be recognized by those of ordinary skill in the art that numerous other embodiments of the inlet doors  38  may be used for achieving the desired results, i.e. a variable flow nozzle, or an adjustable inlet vent, to mention but a few. 
     In one embodiment, the doors  62  are manually adjusted. An operator outside the processor  10  may adjust the position of the doors  62  based upon observations, experience, or other factors. In another embodiment, the doors  62  may be automatically adjusted by a motor  80  (see FIG.  3 ), or other mechanism capable of moving the doors. In such an embodiment, temperature sensors  82  (or other appropriate sensors) may be utilized to sense the temperature surrounding the feed assembly  40 . As the temperature falls below a predetermined temperature the motor  80  could adjust the doors  62  to increase the size of the inlet  28 . Conversely, as the temperature rises above a predetermined temperature, the motor  80  could adjust the doors  62  to decrease the size of the inlet  28 . 
     In yet another embodiment, the inlet  28  may be held constant and the vacuum source  60  may be adjusted to control the temperature surrounding the feed assembly  40 . In such an embodiment, as the temperature  60  falls below a predetermined level, the vacuum source  60  may be controlled to increase the air flow across the droppers  44 . Conversely, as the temperature rises above a predetermine temperature, the vacuum source  60  may be controlled to decrease the air flow across the droppers  44 . 
     Further still, the temperature surrounding the feed assembly  40  may be controlled through a controlled combination of the inlet  28  size and the rate of air flow across the droppers  44 . That is, temperature control may be implemented through a combination of motor  80  control and vacuum source  60  control. 
     In yet another embodiment, the motor  80  control and/or the vacuum source  60  control may be based upon the rate of flow liquid composition into the feed assembly. Liquid level sensors may be utilized to sense the level of liquid composition within the feed assembly. Under normal operation (with all droppers  44  completely open), a certain flow rate (of liquid composition into the feed assembly) will be established. If this rate decreases, such a decrease may be presumed to result from a formation of ice within the droppers  44 . As a result, the motor  80  may be controlled to increase the size of inlet  28  and/or the vacuum source  60  may be controlled to increase the flow of air across the droppers  44 . 
     Several sensors  66  may be incorporated to measure numerous operating values, such as freezing chamber temperature, refrigerant level, etc. These sensors each provide an input signal to control device  68  which monitors the production process and provides control output signals  70  to facilitate automatic production of the frozen beads. For purposes of illustration, these sensors have been included in FIG. 1 simply as dots. It will be appreciated, however, that the actual structure of the sensors will vary in accordance with the actual implementation. 
     Numerous benefits result from the use of the above-described system. In contrast to prior art designs where the freezing of liquid composition in the feed assembly created the need to discontinue the production process while the feed assembly was warmed and subsequently cleaned, the above-described system prevents the liquid from freezing in the feed assembly. Thus, the production process may continue uninterrupted. 
     Additionally, improperly frozen liquid composition represents waste, which must be screened and removed from the uniform beaded product prior to packaging. This waste and the processes associated with removing the waste from the desired product, e.g. operation of separation devices, decreases production efficiency. The present invention eliminates this waste. By use of the novel gas diffusion chamber and vacuum assembly, the need for a separation requirement is successfully eliminated, thus the prior art screening components and the power utilized to operate them are no longer required. 
     In accordance with one embodiment of the system, an air intake filter  90  (see FIGS. 1 and 3) may be disposed at the air inlet  28 . Although illustrated on the inside of the doors  62 , the intake filter  90  may alternatively be positioned on the outside of the doors  62 . Although significant measures are taken to ensure that the environment surrounding the processor  10  is maintained in an extremely sanitary fashion, it has been recognized that certain airborne contaminants may nevertheless be present. As a result, the air intake filter  90  is provided to further sanitize and screen the air that is allowed to flow across the feed assembly  40 , thereby resulting in a more pure and clean frozen product. 
     Consistent with the scope and spirit of the present invention, the material used to form the filter  90 , the filter density, porosity, and other characteristics may be varied. Indeed, the invention is not limited to any of these particulars of the intake filter  90 . Notwithstanding, a filter constructed in accordance with a preferred embodiment of the invention will remove all contaminants 0.2 microns in size or larger. 
     In accordance with yet another aspect of the present invention, the thermal characteristics of the processor  10  are improved. Preferably, the processor  10  is constructed with a double-wall construction, having an inner wall  14  and an outer wall  16 . Previous generation processors have included foam glass insulation between the walls  14  and  16 . However, in accordance with one aspect of the invention, a vacuum jacket is instituted to insulate the liquid refrigerant within the processor  10 . Accordingly a port (not shown) and vacuum source (not shown) may be provided to evacuate the chamber between the inner wall  14  and outer wall  16 . It has been found that such a “vacuum jacket” provides better insulating quality than a foam glass jacket. As a result, the rate at which the liquid refrigerant vaporizes and evaporates is reduced. Thus, a smaller amount of liquid refrigerant is required for the preparation of a given amount of frozen product. 
     IMPROVEMENT OF THE PRESENT INVENTION 
     Having described a cryogenic processor  10  to better define the environment of the present invention, the improvement of the present invention relates to a control system for controlling the operation of the cryogenic processor described above. In this regard, reference is made to FIG.  4  and the appendix attached hereto. FIG. 4 is a diagram of the cryogenic processor  10  showing various control valves. For simplicity, some of the details of the cryogenic processor illustrated in FIGS. 1-3 have been eliminated from the diagram of FIG.  4 . The operation of the control system is computer-controlled, and the flow-charts and logic for controller  100  are described in detail in the Appendix hereto. 
     Broadly, the controller  100  operates to control the operation of the various valves to regulate both the level of liquid nitrogen in the freezing chamber and the liquid composition that is delivered to the feed tray  48 . In one embodiment, the feed tray  48  may be a single tray, for holding a single flavor of liquid composition. There is at least one throttling valve  102  for controlling the introduction of liquid nitrogen into the cryogenic processor  10 . Likewise, there is a valve  104  for controlling the introduction of liquid composition into the feed tray  48 . Both of these valves are controlled by one or more electrical signals output from the controller  100 . 
     In the illustrated embodiment, the controller  100  also generates an output signal that controls a drive motor  106  for an auger delivery system  108 . The auger delivery system  108  includes a screw conveyor that carries frozen beads of ice cream from the bottom of the cryogenic processor  10  upward to chute  109 , where the beads are output for packaging. As illustrated, the mouth of the chute  109  is vertically above the surface level of the liquid nitrogen. Therefore, liquid nitrogen is separated from the beaded ice cream in the auger delivery system  108 . Any trace amounts of liquid nitrogen that may be on the outer surface of the beaded ice cream evaporates therefrom before being expelled from the chute  109 . In this regard, and as is known, liquid nitrogen has a very rapid evaporation rate. 
     The rate of drive motor  106  may be set to depend upon the rate of introduction of liquid composition into the feed tray  48 . 
     In addition to the outputs described above for the controller  100 , the controller  100  has several inputs. These include an input indicative of the level of liquid nitrogen in the reservoir of the cryogenic processor  10 , and an input indicative of the level of liquid composition in the feed tray  48 . The input indicative of the level of liquid nitrogen may be provided through pressure transducer  110 , or in other manners that are well known for sensing liquid levels. Preferably, the surface level of the liquid nitrogen is maintained to be approximately 18-22 inches from the bottom of the feed tray  48 . As the level approaches a distance of approximately 22 inches, the valve  102  may be controlled to allow the introduction of liquid nitrogen into the reservoir at a greater rate. Likewise, as the level approaches a distance of approximately 18 inches, the valve  102  may be controlled to slow the rate of the introduction of liquid nitrogen into the reservoir. It is preferred to maintain the introduction of liquid nitrogen into the reservoir at a relatively constant rate, to prevent over-agitation of the liquid nitrogen within the reservoir. By minimizing the agitation of the liquid nitrogen, smoother and more-spherical beads of beaded ice cream are obtained. 
     The input indicative of the level of liquid composition in the feed tray  48  may be provided through a capacitance probe  112 , or in other manners that are well known for sensing liquid levels. The higher the level of liquid composition within the feed tray, the greater the rate at which the liquid composition is expelled from the droppers  44  (see FIGS. 1-3) that depend from the feed tray  48 . The actual height of the liquid level may depend upon the flavor of ice cream that is being made, as differing flavors may have differing viscosities, as well the size of the frozen bead that is desired. 
     Although not specifically illustrated, another input may be provided to the controller  100  in the form of a feedback measure from the auger delivery system  108 . That is, a sensor may be configured to measure the actual rotational speed of the auger, and this sensed value may be fed back to the controller  100 . 
     In other embodiments the feed tray (see FIG. 5) may be partitioned to hold several flavors of liquid composition, and the final product would be a mix of beaded ice-cream flavors. For example, FIG. 5 illustrates a feed tray  148  having five partitions  202 ,  204 ,  206 ,  208 , and  210 . Each separate partition may be dedicated to a specific flavor. Thus, for example, one partition  202  may be dedicated to vanilla, one partition  204  may be dedicated to chocolate, one partition  206  may be dedicated to strawberry, etc. Vanilla-flavored ice cream may be manufactured by controlling the appropriate delivery valves to deliver only vanilla liquid composition to its partition (i.e., shutting off the delivery of all other flavors). Likewise, chocolate-flavored ice cream may be manufactured by controlling the appropriate delivery valves to deliver only chocolate liquid composition to its partition. Flavored mixtures may be manufactured by controlling the respective delivery valves appropriately. 
     For example, in such an embodiment (not specifically shown) there may be several control valves for regulating the flow of liquid composition into the different partitions of the feed tray  148 . It will be appreciated that each such control valve is separately controlled and regulated based upon the percentage of that particular flavor that is desired in the final beaded ice-cream composition. For example, to make an ice cream product having 75% vanilla and 25% chocolate beads, then the rate of the valve allowing the introduction of vanilla liquid composition into the feed tray  148  is controlled so that the vanilla is introduced into its partition  202  of the feed tray  148  at approximately 3 times the rate that the chocolate liquid composition is introduced into its partition  204  of the feed tray  148 . 
     It will be appreciated that such a multiple partitioned feed tray  148  allows the manufacture of differing flavors of beaded product in successive runs of the cryogenic processor  10 , without having to cleaning the equipment between successive runs. 
     The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment or embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly and legally entitled.