Abstract:
A temperature controlled food service container is formed with an inner portion having side walls and an opening for the receipt of food, and an outer portion having sidewalls spaced from the inner portion with a eutectic gel, disposed between them. A ledge extends from the periphery of the outer portion with a flange extending from the inner portion seated against the ledge; and is held by an ultrasonic bond joining the ledge to the flange. The food container has ribs along the sidewalls of the inner and outer portions. Peripheral channels and ridges are formed respectively on the ledge and flange for welded engagement with each other, the channels having enlarged segments which extend beyond the cross-sectional dimension of a respective ridge received therein. The method for making the food service container includes molding an outer walled shell portion having a ledge with at least one peripheral channel, and molding an inner walled shall portion having a major peripheral flange with at least one peripheral protuberance. Thereafter a eutectic gel is placed into the outer walled shell portion and the inner walled shell portion is placed therein. The peripheral protuberance is indexed into the peripheral channel and the ledge and flange are ultrasonically bonded.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The field of this invention lies within the food pan and container art particularly as it relates to maintaining food at a desired temperature to limit spoilage, and enhance tastiness. More particularly, it lies within the art of maintaining food in a safe and improved temperature environment in a food pan or container. The food pan is surrounded by a medium such as a eutectic gel which can be a highly absorbent polymer. The eutectic gel is exposed to a relative temperature in order to bring the temperature of the eutectic gel to a desired level. Thus, when the food is placed within the pan having the eutectic gel exposed to a previous temperature, it helps to sustain the temperature of the food at a desirable level.  
         [0003]     Such temperature controlled containers and pans utilizing eutectic gels are often used in commercial food service establishments. The food pans and containers with the eutectic gels can be utilized within the field of institutional food service such as restaurants, fast food restaurants, hospitals, schools, banquet facilities, and other related commercial and institutional food service activities. The end result is to provide for a desirable food service as to quality, temperature control, tastiness as well as attractive appearances of the food.  
         [0004]     2. Prior Art  
         [0005]     The prior art with respect to temperature controlled containers includes which have substances such as ice in various forms including dry ice and ice made from water. Utilization of such containers often times is cumbersome and difficult and, of course, requires large volumes of ice.  
         [0006]     Of late, it has been established that containers having a eutectic gel surrounding them or in association therewith such as those items known as ice and heat packs that can be pre-chilled or frozen, can provide substantially superior maintenance of foods in a container. Also, such eutectic gels packs can be used for maintaining heat as well as cooling purposes.  
         [0007]     When using eutectic gels, they should not be exposed to the food, which they are designed to maintain in a temperature-enhanced environment. As a consequence, any leakage of material from a package containing the eutectic gel or a container containing the eutectic gel into the food can be a drawback. In order to eliminate such exposure of food to the eutectic gel, it has been common to provide for an inner and outer shell with a eutectic gel there between.  
         [0008]     The inner shell is utilized to hold the food and is in contact with the food. The outer shell surrounds the inner shell. In between the inner and outer shell, the eutectic gel is placed so that it can be cooled to a particular extent or maintained in any other suitable temperature or heat controlled environment.  
         [0009]     In the past, the utilization of a lip or flange to interface between the inner and outer shells effectuated a sealing contact surface to maintain the eutectic gel between the inner and outer shells. This was effected by various means including adhesives that bonded the two respective inner and outer shells together.  
         [0010]     The utilization of an adhesive or gluing agent was found to be difficult in application and sometimes did not provide for a sufficiently strong and complete seal. This, of course, led to the disassociation of the inner and outer shell and in some cases, a leakage of the eutectic gel into the inner position of the container containing the food.  
         [0011]     This invention particularly enhances the securement of the inner and outer shell by means of an ultrasonic welding process. To this extent, the ultrasonic welding process utilizes an inner and outer shell which are bonded at a weld surface with an inner and outer respective flange, lip or ledge being secured together.  
         [0012]     The inner and outer flanges, lips or ledges respectively have welding flanges, ribs, bands, strips, ridges, rims or protuberances, which can be indexed into welding grooves or channels. The welding channels or grooves receive the protuberances or ridges in an indexed and matched manner substantially around the surface of the main outer flange and inner flange lips or ledges, which extend beyond the periphery of the container.  
         [0013]     When the welding ridges or strips are seated and driven against the surfaces of the channels, they effect an ultrasonic weld that is properly indexed as well as such where it drives against a surface for plastic flow of the materials.  
         [0014]     An enhancement of this invention is the utilization of expanded portions in the welding channels with expansion gaps. These expanded portions or expansion gaps permit the weld to take place without undue displacement by either the heated materials or gases created during the welding process. The gaps, which can be in the form of offsets, depressions, or other expansion areas, allow for the expansion of gas or materials to provide, an effective weld taking place without being dislocated or driving the weldment into a displaced relationship.  
         [0015]     It has been found with the expansion gaps or depressions, that a stronger weld takes place and a significant elimination of failures of the weld have been eliminated.  
         [0016]     A further enhancement of this invention is the utilization of spacers or ribs between the inner shell and outer shell. The spacers or ribs allow for indexing of the inner and outer shell together for proper placement of the eutectic gel as well as orientation during the welding process. Further to this extent, they also enhance and rigidify the overall wall structure of the inner and outer shell to provide for a strengthened composite food container.  
         [0017]     Another feature and objective of this invention is to allow for the stacking of the units both before and after welding of the inner and outer portions. The stacking of the units can be accomplished so that multiple inner or outer shells can be stacked together prior to the welding process. This allows for continuity of the process without the necessity of handling each inner or outer shell on a singular basis so that they can be handled fundamentally on a series basis.  
         [0018]     Another feature of this invention is a ledge or step within the base portion of the completed product formed in the outer shell. This allows for the completed products to be stacked together both when in use and not in use. Thus, multiple units can be handled and placed within a preconditioning temperature environment in order to create a series of them that can then be nested and separated at a later point.  
         [0019]     The improved process relies upon the proper measurement of eutectic gel and any displacement thereof by the inner shell when joined together with the outer shell having the eutectic gel therein. The displacement is accomplished through a certain level to allow for expansion and contraction of the eutectic gel during the various temperatures at which it is used.  
         [0020]     As a consequence, this invention is a significant step as to both the end product and the process in manufacturing the product.  
       SUMMARY OF THE INVENTION  
       [0021]     In summation, this invention comprises a food pan or container which can enhance and maintain food at a desirable temperature by a eutectic gel which is placed between an inner and outer shell which is secured by ultrasonic welding of the two respective shells together. The process for welding the inner and outer shells together is enhanced by respective welding rims, ridges, flanges and grooves or channels having an improved configuration and appropriate indexing orientations.  
         [0022]     More particularly, the invention comprises an improved temperature controlled container or pan for food service in a commercial or institutional environment. The food container is provided with a eutectic gel and a configuration which maintains the food at a desirable temperature once the gel has been chilled, frozen or brought to a temperature that is desired.  
         [0023]     The container is formed by an inner shell and an outer shell. The inner shell has a peripheral rim or flange with a depending lip margin or border protuberance around the rim or flange.  
         [0024]     The outer shell has a complementary peripheral rim or flange in which a series of peripheral channels or grooves are provided which index into ribs as ridges on the flange of the inner container.  
         [0025]     When the two respective flanges of the inner and outer container are brought together and welded, the matching configuration of the respective complementary flanges, with their ridges and channels create an indexing and an improved weldment.  
         [0026]     In order to enhance the welding process, the channels are provided with expansion gaps or indentations. These respective expansion gaps, offsets or indentations create a situation wherein the gas or heated material can expand into the gaps and prevent a dislodgment or displacement of the respective parts through the welding process. The expansion gaps effectively allow for the gas or material to expand therein to thereby enhance the overall welding process.  
         [0027]     A further improvement of this invention is the fact that the inner and outer shell are indexed to each other by ribs which help to align and maintain the process. The maintenance of the ribs and indexing of the inner and outer shell together create a situation which improves the orientation and strengthens the inner and outer shells in their respective relationship for improved strength, stability and improved manufacture and processing.  
         [0028]     The overall process diminishes disorientation and serves to diminish the weakness created during a welding process by displacement of unwanted gas or material. Additionally, the invention orients the eutectic gel and the inner and outer shell together for enhanced and improved maintenance of food therein.  
         [0029]     A further enhancedment is the ability of the inner and outer shells to be serially stacked together before the welding process. After the shells have been welded step or ledge in the base of each outer shell, which allows for nesting and stacking of the containers for proper orientation and storage.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]      FIG. 1  shows an exploded perspective view of the inner and outer shells of this invention.  
         [0031]      FIG. 2  shows a midline sectional view of the entire food container including the inner and outer shells when welded together and provided with eutectic gel between the walls thereof.  
         [0032]      FIG. 3  shows a sectional view of the inner and outer shells as sectioned along lines  3 - 3  of  FIG. 2 .  
         [0033]      FIG. 4  is a view of the inner and outer shells of the container as sectioned through an edge region thereof in order to show the major flanges of the inner and outer shells with their respective rim, or ridges that seat in the channels of the outer shell.  
         [0034]      FIG. 5  is a sectional view through the flange area shown in  FIG. 4  after weldment has taken place.  
         [0035]      FIG. 6  is a fragmented sectional view showing the implacement of the eutectic gel within the outer container prior to weldment.  
         [0036]      FIG. 7  is a fragmented sectional view showing the inner shell being implaced into the outer shell after the eutectic gel has been implaced therein.  
         [0037]      FIG. 8  shows a fragmented sectional view of the welding process whereby ultrasonic energy is applied to the inner and outer shells through a welding horn.  
         [0038]      FIG. 9  shows a fragmented perspective view of the outer shell with the channels in the flange having the expansion gaps.  
         [0039]      FIG. 10  shows a top plan view looking downwardly on the channels shown in  FIG. 9  to exemplify the expansion gaps.  
         [0040]      FIG. 11  shows a sectional view along lines  11 - 11 , with a phantom view of a portion of the inner shell.  
         [0041]      FIG. 12  shows a sectional view along lines  12 - 12 , with a phantom view of a portion of the inner shell.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]      FIG. 1  shows the temperature-controlled food container of this invention in the form of container  10 . Looking at the container  10 , it can be seen that it comprises an outer portion, shell, casing, or residual holder  12 . Seated within the outer portion or shell  12  is an inner portion or shell  14 . The inner portion or shell  14  seats within the outer portion or shell  12  in a relatively fixed and indexed relationship.  
         [0043]     Within the interior portion or shell  14  is a void, space, or food receptacle  16 . The food receptacle  16  receives the food that is to be maintained in the temperature-controlled manner.  
         [0044]     Both of the inner and outer shells  14  and  12  are made of plastic and respectively have an extending major lip flange, rim or ledge. In particular, the outer shell  12  has a lip, flange or ledge  18 . This lip flange or ledge  18  allows for placement of the inner shell thereon and a proper complementary connection as will be detailed hereinafter.  
         [0045]     The inner shell  14  has an overlying lip flange or ledge  20  which can be seen in the figures overlying the lip, flange or ledge  18  of the outer shell.  
         [0046]     The two respective lips or flanges  18  and  20  are sealed together by an ultrasonic welding process. The ultrasonic welding process welds the plastic material together so that it forms a bond for receipt of a material such as a eutectic gel  22  that is placed within the walls between the inner shell  14  and outer shell  12 .  
         [0047]     The walls of the inner shell  14  and the outer shell  12  can be configured in any particular manner of plastic. Thus, they can be configured so as to be of a cylindrical form for receipt of food within a void  16  inside of a cylinder. Other configurations can be such where they have a square cross-section, elongated rectangular cross-section, rectangular configuration in the form of a cross-section, or a rhomboid or diamond cross-section as well as other configurations such as an elliptical cross-section depending upon the particular desired end use.  
         [0048]     The inner shell  14  has a plurality of ribs around the periphery thereof. These particular ribs are shown as ribs  26 ,  28 ,  30 ,  32 ,  33  and  34 . Each of the ribs  26  through  34  has an orientation depending downwardly along the longitudinal dimensions of the inner shell  14 . In this manner, the ribs can be used to provide stiffening and rigidity to the inner shell  14 . Further to this extent, the ribs also provide an indexing of the inner shell to the outer shell  12  when the respective parts are placed together for purposes of joindure and welding. This joindure and welding process is such wherein the ribs when indexed into the inner walls of the outer shell  12  can then be joined in a more facile manner.  
         [0049]     Each of the ribs  26  through  34  have a stepped portion  40  formed as a rounded step like surface. The rounded step like surface is such wherein it allows the stacking of the inner shells  14  in a facile manner prior to there being welded to the outer shells  12 . Thus, a stack of inner shells  14  can be laid up into a significant stack or pile thereof without binding on the interior surfaces to the extent where they are hard to remove from each other. Thus, the nesting of the inner shells  14  during the stacking process is such wherein they can be easily divided or separated without any extent or of binding frictional engagement, in as much as the surfaces of the steps  40  are rounded and seat on the edges of the lip or ledge  20  of the inner shells  14 .  
         [0050]     The seating of the step  40  when the inner shells  14  are stacked or nested is against the rounded edge surfaces or corners  44  surrounding the interior. In this manner, the edge of the ribs  26  through  34  ride against the surrounding interior peripheral surface  44  of the inner shell  14 . This allows for facile and easily removed displacement of the inner shells  14  when stacked together prior to being separated for welding to the respective outer shell  12  to which it is later connected.  
         [0051]     In order to have an indexing of the outer shell  12  to the inner shell  14 , a second series of ribs are provided. These ribs comprise longitudinally extending ribs  50 ,  52 ,  54  and  56 . The ribs  50  through  56  are such wherein they provide for the nesting of the inner shell  14  to the outer shell  12  in a spaced manner. This enhances the overall nesting and placement of the shells  12  and  14  both prior to welding, and after the welding process for rigidification of the walls of the outer shell  12  and the entire product once it has been implaced and welded.  
         [0052]     Once the entire product has been welded as shown in  FIG. 8 , the product can then be stacked in its completed form and nested by means of a step, ledge, or peripheral inset  60 . This peripheral inset or step  60  allows for a stacking of the respective outer shells  12  in both the incomplete and separate relationship prior to welding. This enables a stacking of the containers  10  with food in the voids  16  as well as without the food in the voids  16 . This also provides for easier handling and overall facile movement of a plurality of containers  10 .  
         [0053]     Between the walls of the outer shell  12  and inner shell  14 , is a eutectic gel. This gel can be of a polymeric substance as well as being formed of either an organic or an inorganic substance. In this particular case, the gel is of an organic material and can be placed into a surrounding cold area in order to lower the temperature of the gel. Various gels can be utilized having various chemical compositions. The one criteria is that the gel should be able to undertake a significant drop in temperature and retain it to a greater degree than other materials. Such gels are known in the art for providing a cold retention or hot retention property. The gel can be reused or refrozen multiple times.  
         [0054]     The gel in this case is an organic material formed of cellulose such as carboxy methyl cellulose and water. The range of it can be in the amount of eighty to ninety-nine percent (80%-99%) water and one to nineteen (1%-19%) cellulose ether. A preferred mixture is 97.2% water and 2.4% cellulose ether.  
         [0055]     As a general consideration, the container  10  is placed with the opening to the void  16  in a downward orientation. It is placed in a freezer or a low temperature environment that can be such where the temperature is lowered. Generally, the container  10  is placed in a freezer with a temperature of 0 degrees Fahrenheit to 20 degrees Fahrenheit for an extended period of time which could be as long as 8 hours. The container is then removed and food products placed therein. The container  10  can then retain the food temperatures for an extended period of time when used in a normal, ambient condition.  
         [0056]     Container  10  comprises the outer shell  12  and inner container or shell  14  which is formed by initially molding the respective portions  12  and  14  from a high impact plastic. This can be a high impact ABS plastic. However, it can be molded from any particular suitably strong plastic in various molding processes including compression molding, injection molding, rotational molding, and other suitable types of molding processes.  
         [0057]     The net result for the two respective container shells or portions  12  and  14  should be such wherein after they have been joined together, they are properly held so that they can form a unitary food container which will serve to maintain temperature within the container  10 .  
         [0058]     In order to join the two respective container shells or portions  12  and  14  together, a sonic welding process is utilized. The joindure takes place by reason of a sonic welding head or horn shown in  FIG. 8  proceeding downwardly and welding the outer major flange  20  of the inner shell  14  to the outer major flange or ledge  18  of the outer shell  12 .  
         [0059]     Initially, an operation shown in  FIGS. 6 and 7  is utilized. This encompasses the disposition of a eutectic gel that can be an organic or inorganic gel into the outer shell  12 . The outer shell  12  is held on its flange, ledge or major lip  18  by a jig, peripheral support or other means to support the outer shell  12  in a fixed manner. This can be seen in the form of jig, fixture or securement peripheral holder  80  shown in  FIGS. 6, 7  and  8 .  
         [0060]     With the outer shell  12  in place, eutectic gel  22  is disposed within the shell  12  by means of a flow from a supply that is controlled by a handle  84  operating a valve mechanism  86  to provide for the flow into the outer container  12 . The handle  84  is shown moving in the direction of arrow  88  by a manual articulation. However, any suitable valving process can be utilized for purposes of allowing the flow  22 , of the eutectic gel into the outer container. For instance, a transducer, solenoid, electrically operating valve or any other suitable means can be substituted for the valve  86  which provides for the flow into the outer shell  12 .  
         [0061]     In order to permit a flow of the eutectic gel  22  into the shell  12  to a suitable volume, the shell  12  can be weighed with a tare weight and then the additional eutectic gel weight calibrated and provided for to a suitable weight. The particular weight will then establish the amount of gel  22  that is in shell  12 .  
         [0062]     With a suitable amount of gel, which has been shown at level  90  in  FIG. 7 , the inner shell  14  is disposed downwardly as, shown in the direction of arrow  94 . This serves to drive the gel  22  upwardly alongside the inner walls of the container to a level suitable for providing thermally controlled eutectic gel for container  10 .  
         [0063]     The respective ribs  26  through  34  for the inner shell  14  and the ribs  50  through  54  of the outer shell  12  serve to guide the two respective inner and outer shells in an indexed manner. They also serve to provide support and structural strength after the containers  10  have been made or formed. Further to this extent, the shoulders  40  as previously described allow for a stacking of the inner shell  14  in a suitable stack for handling as well as manufacturing movement.  
         [0064]     When the inner shell  14  has been moved in the direction of arrow  94  into the outer shell  12 , it thereby displaces the eutectic gel  22 . The gel is driven to a suitable level such as level  98  shown in the  FIG. 8  sectional view and the  FIG. 2  sectional view of completed container  10 .  
         [0065]     After the inner shell  14  and outer shell  12  are held together as shown in  FIG. 8 , a welding horn  100  having a drive forcer  102  moves in the direction of arrow  104  for ultrasonically welding the respective shells  12  and  14 . This is accomplished by a horn head  108  that is driven under the force of pressure by the drive force  104  and ultrasonic welding imparting energy to the horn  108 . Such ultrasonic welding processes are known in the art from the standpoint of maintaining and welding such items that can be formed of plastic and other materials.  
         [0066]     The enhancement of the welding process is accomplished by providing multiple or singular, ribs, ridges, strips, lands or rims in the way of a peripheral convex protuberance shown in  FIGS. 2, 4 ,  5 , and  12 . These ridges can be seen in  FIG. 4  prior to the respective inner and outer shells being driven together. In this particular instance, a first interior ridge having a V-shaped cross-section, which circumscribes the periphery of the major flange or ledge  20  is shown. This ridge can be defined as V-shaped or other suitably shaped rib  114  that generally surrounds the major ledge  20 . A smaller rib, protuberance or flange  116  is shown with a second smaller flange  118 . Both of these flanges are of a V-shaped configuration and substantially surround the periphery of the major ledge or flange  20 .  
         [0067]     A second larger peripheral rib or protuberance  120  is shown. The rib or protuberance  120  has an angular portion as seen in  FIG. 11  in the form of an angular wall  122  and a fundamentally vertical wall  124  or upright wall which extends and is relatively normal to the plane or region of the major flange or ledge  20 .  
         [0068]     The major welding ribs  114  and  120  are received into grooves, channels or peripheral depressions shown in the major flange  18  of the outer shell  12 . In particular, a groove or channel  130  receives rib  114 . A peripheral channel or groove  132  serves to receive rib or protuberance  120 .  
         [0069]     The respective rib  120  and groove  132  are formed so that when the rib  120  is driven into the groove  132 , it tends to engage a sloping surface  136  as shown in  FIG. 11  with the relatively normal or upright surface  124 . The net result is to provide a frictional engagement that is driven together while at the same time the ultrasonic welding process takes place. This tends to displace the material of the sloping surface  136  and upright surface  124  while at the same time creating a tightened weld, which is secured in a tight, secured relationship.  
         [0070]     Looking more specifically at  FIGS. 9, 10  and  11  in conjunction with  FIGS. 4 and 5 , it can be seen that the inner channel or groove  130  of the major flange  20  is shown as a relatively V-shaped cross-sectional configuration. However, the configuration can be of any suitable cross-section so long as it can receive the welding rib  114 . Here again, the welding rib  114  can be of any suitable configuration as long as it can be matched generally to the groove or channel  130  or made to flow through sufficient ultrasonic bonding strength.  
         [0071]     A special feature of this invention is the outer groove  132 , which can also be emulated with the inner groove  130  having the same configuration. The outer groove  132  has a plurality of flow gaps, spaces, or expansion gaps  160 . These gaps  160  permit an expansion of any gases or plastic material during the welding process. In effect, they allow for flow movement or gas displacement so that any gas or flow movement will not drive the peripheral rib  120  out of its bonded relationship through a fluidic or other material displacement of the materials comprising the rib or peripheral protuberance  122 .  
         [0072]     The number of gaps, spaces, offsets or displacement receipt areas  160  can be modified and changed depending upon the respective amount of displaced material during the welding process or plastic material as finalized. The movement of the material into the gaps  160  or offsets, permits a well-received joindure without a lessened displacement of the material of the rib or peripheral protuberance  120 . In this manner, the respective major flanges  20  and  18  are joined together in a tightened manner. Further to this extent, the respective tightened manner of the grooves or channels  130  and  132  against their respective ribs or peripheral protuberances  114  and  120  is secured so that the major outer flange  20  overlaps and is relatively sealed to the inner shell  12 . This can be more readily seen in  FIG. 5 .  
         [0073]     Other suitable types of grooves, channels or other receipt peripheral features can be utilized depending upon the material to be welded and the respective flow characteristics produced by the ultrasonic welding process and the particular welding horn such as welding horn  100 . Also, various displacement gaps  160  can be utilized such as those that would be of a curved, stepped, angular, depressed, or other suitable configuration. The cross-section of the respective gaps  160  can be displaced downwardly into the groove to a further extent, laterally as shown in the figures, or in a stepped configuration such that the cross-section when matched with the peripheral ribs  114  and  120  maintain a suitable connection therebetween while, at the same time, allowing displacement of fluidic plastic or other materials during the formation process.  
         [0074]     Once the respective inner shell  14  is joined to the outer shell  12 , with the eutectic gel therein, it can then be used. Usage is such where the entire container  10  is generally utilized to maintain cold temperatures of food. However, container  10  can be utilized for various functions including the maintenance of heat of food maintained therein. This would generally be accomplished by heating the eutectic gel or other interior material to a certain temperature for maintenance of that temperature. In such cases, the shells  12  or  14  must be formed to allow sufficient expansion and contraction to prevent breakage. A flexible inner and or outer shell  14  and  12  can provide expansion by flexible walls or sufficient space to allow such expansion.  
         [0075]     In order to maintain foods at a lower temperature, the container  10  is placed with the opening  16  downwardly into a freezer or other cooling medium with a temperature of 0° Fahrenheit to 20° Fahrenheit (minus 18° C. to minus 28° C.) for a significant period of time. It has been found that an 8 hour freezing process helps to maintain improved cold retention.  
         [0076]     Container  10  is then removed and food products are added thereto at a lowered temperature. The container  10  can be utilized to maintain food temperatures at a reduced temperature for an extended period of time when used in normal ambient conditions.  
         [0077]     Further to this extent, the food containers can be held by the outer shell  12  peripheral flange  18  in a rack, web, or other suitable support on the peripheral flange  18  so as to support it for food service for an extended period of time. To this extent, the containers can also be stacked together by the utilization of the step, indention or respective inner peripheral ledge  60  surrounding the base thereof for purposes of stacking one container  10  on top of the other.