Abstract:
A process and apparatus for coating a food, confectionery or pharmaceutical product wherein the product is prepared in rotary pans and wherein separate adjustable double piston metering pumps are used to automatically supply a coating substance to each pan on a predetermined schedule.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is generally directed to processes and devices utilized for coating products and especially sugar coatings to products including food, confectionery and pharmaceutical products and more specifically to adjustable double piston metering pumps which are used to supply a coating solution to rotating pans in which a product is retained and wherein the coating solution is supplied by the pumps on a predetermined schedule. 
     2. Brief Description Of The Related Art 
     The process and apparatus of the present invention may be utilized in substantially any coating of a food, confectionery or pharmaceutical product, however, the invention has been specifically developed for use in sugar panning processes wherein the product to be coated is contained in a revolving cylinder, referenced in the industry as a “pan”. In sugar panning, numerous thinly applied layers of solution consisting of mixtures of sugar, water, corn syrup, various gums and coloring agents are applied to the product. Each layer or dosage of the coating solution is measured, applied to the product and allowed to “distribute” within the product before the product is dried using either hot or cold air, depending whether the coating process is a “Hot Process” or a “Cold Process”. The number of layers or dosages applied is predetermined and the processes of coating continues successively until the predetermined number of coatings are applied to the product. 
     The process of applying liquid solution, allowing distribution time and subsequent drying is repeated numerous times until a desired appearance or size of the finished product is obtained. This may require from twenty to several hundred applications of the coating solution depending upon the particular product and the original intent for the panning of the product. Typically, confectionery items are coated with a crunchy candy shell which is usually colored, chocolate confections are coated to prevent melting and pharmaceutical products are made more palatable for consumer consumption. 
     Substantially all sugar panning is done in one of two types of equipment, conventional pans or automated pans. Automated pans are generally used by companies which specialize in panning in large mass utilizing batch processes of products in the one thousand to three thousand pound range. The pans are extremely large and the dosing functions are generally computerized such that the introduction of solutions, drying times and the like are automated. Automated pans are inherently more expensive than conventional pans and can easily cost in the hundreds of thousands of dollars. 
     Conventional pans are smaller and less expensive and process batch sizes from several pounds for laboratory uses up to several hundred pounds for commercial production models. The relatively small batch yield and inexpensive cost of conventional pans normally require that manufactures utilize a plurality of pans in series to accomplish coating tasks. Conventional pans are advantageous for processing multiple batches in various flavors and colors simultaneously. 
     Conventional pans are currently not automated for sugar panning. Dosing and control of drying air is done manually. Typically an operator proceeds from one pan to the next so as to control both the dosing and air supply to each pan in sequence. At each pan where the air is turned of, the coating solution is measured and poured into the revolving pan. The solution is allowed to distribute with the material to be coated before drying air is supplied. This process is repeated at each pan until the desired number of coatings is obtained. Unfortunately, extreme care must be taken so that the coating solution supplied to each pan is supplied not only in equal amounts but so that the amount of distribution time that the coating solution has with the product and the amount of drying time remains equal for all pans in a series of pans in order to provide a uniform product. A typical skillful operator may operate as many as fifteen pans in sequence. 
     In view of the foregoing, in the use of conventional sugar panning equipment, there is no method or apparatus for insuring uniformity of the coatings applied to products from one pan to the next and a great deal of reliance is placed upon the effective skills of an operator. 
     SUMMARY OF THE INVENTION 
     The present invention was developed in view of the shortcomings outlined above with respect to limitations of coating processes utilizing conventional panning equipment. The invention provides both a process and metering pump for automatically supplying, to each pan in a series of pans, a predetermined dose of coating solution at predetermined timed intervals so as to ensure uniformity between the quantity of coating solution introduced into each pan, uniformity at distribution time of the solution within each pan, and uniformity of drying time for each pan in a series of pans. To this end, the present invention includes a coating solution supply assembly which is adapted to be mounted adjacent a conventional pan for supplying predetermined quantities of coating solution to the pan at predetermined time intervals. 
     Each coating solution supply assembly of the present invention includes a unique pan pump formed as a double piston metering and supply pump. Each pump includes a first cylinder chamber having a first metering piston member mounted therein wherein the piston member is adjustable relative to a piston rod which extends through the cylinder. The piston rod moves with the metering piston from a first position for introducing a control fluid into the chamber defined thereby to a second position for discharging the control fluid from the chamber. This action simultaneously causes the discharge of a coating solution from a separate cylinder defining a food grade coating solution supply chamber. The piston rod extends through the first chamber and into the separate second coating solution supply chamber which receives the coating solution. The coating solution supply chamber is maintained spaced from the metering chamber so that the operating or control fluid for the pan pump never contacts the coating solution thus insuring the sterility of the coating solution which is pumped from a supply source to a distribution header. The distribution header is connected in fluid communication with an outlet of the coating solution supply chamber of the pan pump. The piston rod is also connected to a second piston mounted within the coating solution supply chamber. 
     As the first metering piston member is moved by a control fluid within the metering chamber, the piston in the coating solution supply chamber is first moved in a direction to draw a coating solution from a supply container through a one-way check valve and into the solution supply chamber of the pan pump. Once the metering piston has been moved to a fully open position such as by the introduction of a pneumatic source into the chamber of the metering cylinder, the metering piston is activated by the pneumatic source to drive the piston rod to force coating solution out of the chamber of the coating supply chamber through another one-way check valve and to the distribution header. The effective stroke of the metering piston is changed by moving the piston member relative to the piston rod such as by utilizing a threaded engagement between the metering piston member and the piston rod. The effective stroke may also be controlled by the supply of pneumatic air or other fluid to the metering chamber by an appropriate valve and controller. 
     To maintain the solution supply chamber clean and operative, a source of cleaning and lubrication solution and is connected to the coating solution chamber. Cleaning lubricating solution is periodically introduced into the chamber on an opposite side of the piston from the face of the piston which is in contact with the coating solution. The cleaning and lubricating solution may be recycled over a period of time. 
     The coating solution supply assembly is designed to be mounted on a standard or mobile support so as to be spaced adjacent to an opening to a conventional pan. The distribution header extends outwardly from the pan pump and into the pan and is provided with a plurality of nozzles for distributing a coating solution throughout the volume defined by the pan. 
     A controller is provided such that after a predetermined quantity of coating solution is introduced into a coating pan, drying air is not introduced into the pan until a predetermined residence time for the coating solution has been achieved. Thereafter, the controller activates the supply of either hot or cold air to the chamber allowing the coating to solidify as the pan rotates. After a predetermined time, the supply of drying air is terminated and a subsequent injection of coating solution is introduced into the pan. The cycle is repeated until a predetermined coating has been applied to the product. 
     It is the primary object of the invention to enable conventional sugar coating pans to be operated in an automated manner utilizing coating solution supply assemblies which are operable to supply a coating solution through a double piston pan pump in such a manner that the coating solution is introduced into a pumping, dispensing or injection chamber under conditions wherein the food grade solution is retained free from exposure to any elements which may otherwise contaminate the solution and wherein the quantity of solution may be easily adjusted by adjusting a separate metering piston which is remote from the food grade dispensing chamber. 
     It is a further object of the present invention to provide a method and apparatus whereby conventional sugar pans may be operated and supplied with coating solutions in a manner in which coatings are uniformly applied to products within the pans. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective illustrational view of a conventional sugar pan having a coating solution supply assembly mounted adjacent thereto in accordance with the teachings of the present invention. 
     FIG. 2 is a partial side elevational view of the conventional pan and coating solution supply assembly of FIG. 1 showing in greater detail the components of the coating solution supply assembly of the present invention. 
     FIG. 3 is an enlarged side elevational view of the adjustable double piston metering pump utilized with the coating solution supply assembly of the present invention. 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 3 showing the double piston members and double chambers of the pan pump of the present invention. 
     FIG. 5 is a cross sectional illustrational view showing the metering of a predetermined amount of coating solution into the coating solution pumping chamber of the pan pump during a time when drying air is being supplied to product within the coating pan. 
     FIG. 6 is a view similar to FIG. 5 showing the termination of drying air to the pan and the introduction of the coating solution from the pan pump to the product within the rotary pan. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With continued reference to the drawing figures, the coating solution supply assembly  10  of the present invention is shown mounted to a standard or other support  11  adjacent to a conventional sugar pan unit  12 . The sugar pan unit includes a base  13  to which is rotatable mounted a somewhat cylindrical pan  14  which is inclined such that the inner chamber  15  defined thereby is angled upwardly relative to the vertical such that product “P” is contained beneath an opening  16  and within the chamber of the pan. The pan  14  is a conventional coating pan of the type which may enable processing of anywhere up to several hundred pounds of product. The pan is mounted on a rotating shaft  18 , FIG. 2, driven by a motor (not shown) mounted within the base  13 . 
     To harden the solution which is introduced into the pan  14 , a drying air duct  20  is provided having a nozzle portion which extends into the chamber  15 , as shown generally in FIGS. 5 and 6. The configuration of the drying duct and nozzle may be varied depending upon the coating process. Each duct is connected to a central source of either hot or cold drying air. 
     In the drawing figures, the coating solution supply assembly is shown as being mounted to a fixed standard  11 . It should be noted that the assembly may also be mounted to moveable supports so that each assembly may be moved from one pan to another, as may be required, or so that the relationship between assemblies may be altered depending upon the environment in which the coating process is taking place. 
     Each coating solution supply assembly includes a coating solution supply container  24  in which a coating solution “S” is retained. The container may include appropriate markings to indicate the volume content of solution. The solution is withdrawn from the container  24  and pumped through a distribution header  25  which extends inwardly of the chamber  15  of the coating pan  14 . The distribution header may include a plurality of spray or drip nozzles  26  which, in some embodiments, may include adjustable control valves  28 . The metering and supply of the solution is controlled by a pan pump  30  which is mounted to the standard  11 . 
     The pan pump  30  is a double piston metering pump including a metering chamber or cylinder  32  and a pumping or coating solution supply chamber or cylinder  34 . A first metering piston  35  is mounted within the metering chamber  32  in such a manner that it may be adjustable relative to an elongated piston rod  36 . In the drawing figures, the piston  35  is shown as being threadingly engaged with a threaded portion  37  of the piston rod  36  such that rotation of the piston rod relative to the piston will vary the effective stroke length of the piston  35  within the chamber  32 . In this manner, the effective stroke length of a second piston  38  mounted within a pumping or coating solution supply chamber  34  is adjusted. The piston  38  is mounted to the upper end of the piston rod  36  such that the piston  38  and the piston  35  move simultaneously with one another. The piston rod extends through an elongated seal  39  which extends between the cylinders  32  and  34  so as to prevent contamination of the cylinder chamber  34 . 
     The movement of the metering piston  35  is controlled by a pair of pneumatic lines  40  and  42  which extend through openings  43  and  44 , respectively, into the chamber  32 . Each of the pneumatic lines are connected to a solenoid valve  45  which controls an air supply to the lines. The valve is electrically connected to a controller  50  which is connected to an appropriate on-off switch  48 . The controller  50  may be used to control the effective stroke and thus the quantity of solution which is to be pumped into the chamber  15  of the pan  14  during each pumping cycle of the pan pump  30  as well as to control the supply of drying air. 
     As shown in drawing FIGS. 4 and 5, a fluid inlet line  52  extends within the solution supply container  24  and is connected to an inlet  54  into the chamber  34  through a first one-way check valve  55 . When the piston  38  is moved away from the inlet  54 , a partial vacuum is created within the chamber  34  thus drawing the coating solution “S” from the container  24  and into the chamber  34 . The stroke is effectively controlled by the metering piston  35  and its movement within the chamber  32 . In FIG. 5, the piston  34  is being driven downwardly by a pneumatic source such as air supplied through pneumatic line  42 . Air below the piston is bled from the lower portion of the chamber through pneumatic line  40  which functions as an exhaust line until the effective downward stroke of the piston  35  is achieved. At this point in time, the valve  45  is reversed thus driving air through the pneumatic line  40  and moving the piston  35  upwardly and thus moving the piston  38  upwardly so as to discharge solution “S” from within the coating solution supply chamber  34 . The solution is prevented from entering the container  24  because of the one way check valve  55 . The discharging fluid passes through a second one-way check valve  56  and into the distribution header  25  wherein the solution is introduced within the chamber  15  by way of the nozzles  26 . 
     As previously discussed, the effective amount of coating solution can be controlled not only by predetermining the position of the piston  35  within the chamber  32  but also by varying the effective stroke length of the piston  35  by way of air supplied to the metering chamber  32 . Pumping of the solution from the chamber  34  is illustrated in drawing FIG.  6 . 
     Also shown in FIGS. 5 and 6 is a source of lubricant and cleansing agent which is introduced in a cyclic manner into the lower portion of the solution pumping chamber  34 . The solution is contained within an enclosed container  60  which is connected by supply line  62  through an inlet opening  64  in the side wall of the chamber  34 . The fluid may be a vegetable oil type fluid which is utilized to provide both a lubricant source within the pumping chamber as well as a cleansing source. 
     It should be noted that as opposed to applying a single outlet  54  from the pumping chamber  34 , a separate inlet may be provided for drawing solution “S” from the container  24  through check valve  55  into the chamber  34  and a separate outlet may be provided to which the check valve  56  is connected so that fluid is discharged through the separate outlet to the distribution header  25 . 
     Utilizing the apparatus of the present invention, the controller  50  is utilized as a timer. An initial determination is made to set the position of the metering piston  35  relative to the piston rod  36 . The controller  50  also includes a connection to a drying air controller  70 . Whenever solution is being introduced into the chamber  15  of the pan  14 , the dryer is normally deactivated so as to allow a predetermined residence or distribution time of the solution within the product “P” prior to drying air being introduced to affect drying. 
     Utilizing the pan pump  30  of the present invention, no contamination of the coating solution is possible as the metering is effectively accomplished in the lower portion of the pan pump with the metering piston  35  operating within the metering chamber  32 . Therefore, the sterility of the coating solution is maintained throughout the coating process. 
     Utilizing the present invention, uniform quantities of solution are introduced into the pans  14  and the distribution time of the solution within the product and the drying time is accurately assured thereby insuring uniformity of the coated product from one pan to another. 
     The foregoing description of the preferred embodiment of the invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiment illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their equivalents.