Patent ID: 12226052

DETAILED DESCRIPTION

Exemplary embodiments of this disclosure are described below and illustrated in the accompanying figures, in which like numerals refer to like parts throughout the several views. The embodiments described provide examples and should not be interpreted as limiting the scope of the invention.

Referring toFIGS.1and2, a heat retentive server10of a first embodiment of this disclosure is described in the following. The server10includes an upwardly and outwardly extending polymeric ring14mounted to a periphery of a central disk assembly18, so that the server may be characterized as being in the form of a round tray or plate-like structure, although numerous other configurations are within the scope of this disclosure, as will be discussed below. Referring also toFIG.2and as discussed in greater detail below, at least one internal metallic plate, or more specifically a metallic disk22, of the disk assembly18may be heated by way of electromagnetic induction while the server10is upon an activator5containing one or more induction coils (not shown). Thereafter, or at any other suitable time, a dish, such as a plate6, may be placed centrally upon the upper surface of the disk assembly18so that the ring14extends around at least a lower portion of the plate. The dish, or more specifically the plate6, may be made of china or other acceptable materials. The plate6, as well as food7on the plate, may be covered with an insulated, dome-shaped cover8having a lower periphery that substantially seals against an upper periphery of the ring14. Typically the plate6and food7are covered with the insulated cover8from shortly after the point in time at which the plate with food is placed upon the server10to shortly before the point in time at which the food is to be consumed. Examples of covers, or lids, are disclosed in U.S. Pat. Nos. 4,982,722, 5,603,858 and 6,670,589, and the disclosure of each of these patents is incorporated herein by reference in its entirety. As an example of an advantage that will be discussed in greater detail below, the washed dish6may not need to be preheated prior to placing the food7thereon, because the server10may provide sufficient heat energy so that the food7may have a serving temperature of at least 140° F. after one hour irrespective of whether the dish is preheated or at room temperature when the food is placed thereon.

Referring in greater detail toFIGS.1and2, the disk assembly18includes a body that is typically in the form of polymeric upper and lower shells26,28that are fixedly connected to one another. The shells26,28may be connected in any suitable manner. For example, the ring14is typically mounted to the periphery of the disk assembly18in a manner that at least partially holds (e.g., clasps) the shells26,28together, as will be discussed in greater detail below. In the first embodiment, the upper and lower shells26,28are also fixedly mounted to one another at annular inner and outer joints32,34, wherein the inner and outer joints32,34, like many other features of the server10, extend around and are coaxially arranged with respect to a central axis38of the server.

For each of the inner and outer joints32,34, the upper shell26defines a downwardly oriented annular receptacle that is in snug receipt of an upwardly oriented annular protrusion of the lower shell28. Prior to mounting the shells26,28together, the downwardly oriented annular receptacles of the upper shell26would be downwardly open, since they would not yet be in respective receipt of the upwardly oriented annular protrusions of the lower shell28. Each of the downwardly oriented annular receptacles of the upper shell26is defined between a pair of downwardly extending, concentric portions of the upper shell.

For each of the inner and outer joints32,34, there may be an annular interference fit between the annular receptacle of the upper shell26and the annular protrusion of the lower shell28. In addition and/or alternatively, for each of the inner and outer joints32,34, there may be an annular connection (e.g., a sonic weld) between at least the tip of the annular protrusion and the apex of the annular receptacle of the joint. For each of the inner and outer joints32,34, the positions of the annular receptacle and annular protrusion of the joint may be reversed. The upper and lower shells26,28may be connected to one another in any other suitable manner.

The disk assembly18includes an outer chamber42that extends around an inner chamber44of the disk assembly. The chambers42,44are defined between the upper and lower shells26,28, so that the inner chamber44is circumscribed by the inner joint32, the outer chamber42circumscribes the inner joint, and the outer joint34circumscribes the outer chamber. The induction-heatable metallic disk22is positioned in the outer chamber42. The inner joint32extends through a central hole in the metallic disk22.

The metallic disc22is enveloped (e.g., partially enveloped or fully enveloped) by thermal material that is within the outer chamber42. In the first embodiment, the thermal material is layered, so that there are layers50,52,54of thermal material (e.g., plies50,52of insulating material and a ply of buffering material54) that are in a stacked configuration, wherein each of the layers50,52,54is in the form of a disk with a central hole through which the inner joint32extends, and the metallic disk22is positioned within the stack of layers50,52,54.

The layers50,52,54of thermal material are adapted for both retaining heat in the metallic disk22, and directing heat from the metallic disk to the plate6, or other object(s), that are upon the upper surface of the upper shell26. More specifically and regarding the conductive flow of heat from the heated metallic disk22in an axial direction that extends along and parallel to the central axis38of the server10, the rate of conductive heat flow (e.g., heat flux) through the upper layer54of buffering material and the upper shell26exceeds the rate of conductive heat flow (e.g., heat flux) through the lower and intermediate layers50,52of insulation and the lower shell28.

More specifically and in accordance with the first embodiment, outward heat transfer through the lower shell28is not desired, and such outward heat transfer through the lower shell may be characterized as being heat loss to the system. Also, it is typically desirable for the lower shell28not to be hot to the touch so as not to cause a burn injury when the metallic disk22is hot. Accordingly, the lower and intermediate layers50,52of insulation are adapted for substantially restricting outward heat transfer through the lower shell28.

In contrast, controlled, long-term, substantial outward heat transfer through the upper shell26is desired. Accordingly, the layer54of buffering material serves as a buffer between the metallic disk22and the upper shell26. In the first embodiment, the layer54of buffering material fills the gap between the metallic disk22and the upper shell26, and the layer of buffering material is adapted for gradually transferring heat from the metallic disk to the upper shell, wherein the heat transfer through the layer of buffering material is slow and gradual so that, while the metallic disk is sufficiently hot, the temperature of the underside of the upper shell can exceed the heat deflection temperature of the material from which the upper shell is constructed, without damaging the upper shell.

In the first embodiment and as will be discussed in greater detail below, the disk assembly18may be configured (e.g., the layers50,52,54are adapted) for providing predetermined conductive heat transfer from the metallic disk22to the body (i.e., the upper and lower shells26,28) of the disk assembly, so that, in response to the metallic disk being heated by electromagnetic induction to greater than the heat deflection temperature of the body: the temperature of at least a portion of the body, namely at least a portion of the upper shell26(e.g., the portion(s) of the upper shell that are in relatively close proximity to the layer54of buffering material) become(s) greater than the heat deflection temperature of the body; and in contrast the temperature of at least a portion of the body, namely the lower shell28, does not exceed the heat deflection temperature of the body. Other configurations are also within the scope of this disclosure.

As mentioned above, the metallic disk22may be heated by electromagnetic induction, and the disk assembly18is adapted so that there is predetermined conductive heat transfer from the heated metallic disk, through the layers50,52,54, and through the shells26,28. In this regard, the disk assembly18of the first embodiment includes different features that are cooperative for providing the predetermined conductive heat transfer, and the cooperative features generally include the selection and arrangement of the layers50,52,54, which will be discussed in greater detail below, as well as provisions made in an effort to exclude, or minimize, any water in the heat conductive paths defined by the disk assembly. For example, each of the lower and intermediate layers50,52of insulation may be impregnated with synthetic amorphous silica to produce a hydrophobic affect, as will be discussed in greater detail below. In this regard, when the servers10are used in conjunction with serving food7, it is typical for the servers to be washed with soap and water, or the like, after each use; therefore, the servers may be repeatedly wetted and/or immersed in water.

In accordance with the first embodiment, at least some of the adjacent structures in the disk assembly18are in opposing face-to-face contact with one another in a manner that inhibits any water from becoming intervened in at least some of the heat conductive paths that extend in the axial direction of the disk assembly. More specifically, a broad, substantially planar, annular, lower face of the lower layer50of insulation is substantially parallel to and in opposing face-to-face contact with a broad, substantially planar, annular, upper face of the lower shell28. Similarly, a broad, substantially planar, annular, upper face of the upper layer54of buffering material is substantially parallel to and in opposing face-to-face contact with a broad, substantially planar, annular, lower face of the upper shell26.

The metallic disk22is positioned between the lower and upper layers50,54. More specifically, the metallic disk22is positioned between the intermediate and upper and layers52,54. A broad, substantially planar, annular, upper face of the intermediate layer52of insulation is substantially parallel to and in opposing face-to-face contact with a broad, substantially planar, annular, lower face of the metallic disk22. Similarly, a broad, substantially planar, annular, lower face of the upper layer54of buffering material is substantially parallel to and in opposing face-to-face contact with a broad, substantially planar, annular, upper face of the metallic disk22. A broad, substantially planar, annular, lower face of the intermediate layer52of insulation is substantially parallel to and in opposing face-to-face contact with a broad, substantially planar, annular, upper face of the lower layer50of insulation. The stack, which includes the metallic disk22and the layers50,52,54, may be arranged differently. For example, the lower and intermediate layers50,52of insulation may be replaced with a single layer of insulation, or any other suitable arrangement of the insulation may be utilized.

In accordance with the first embodiment, the primary heat conductive paths defined by the disk assembly18are associated with the outer chamber42, since the metallic disk22is therein; therefore, the outer chamber is sealed in a manner that seeks to prevent water from entering the outer chamber. In this regard, the seal present at each of the inner and outer joints32,34may be enhanced by and/or at least partially provided by a gasket, or any other suitable sealing feature, in any suitable configuration. More specifically, an intermediate O-ring60is adjacent the outer joint34, and an annular washer64is adjacent the inner joint32. As a more specific example, the intermediate O-ring60is housed in an annular channel of the lower shell28, and the intermediate O-ring is compressed between an annular lower wall of the lower shell's channel and an annular lower surface of the upper shell26. As another specific example, an annular inner portion of the washer64is compressed between an annular, upwardly facing shoulder of the lower shell28and a downwardly oriented annular protrusion of the upper shell26. Upper and lower surfaces of an annular outer portion of the washer64are respectively in opposing face-to-face contact with an annular inner portion of the lower face of the metallic disk22and an annular inner portion of the upper face of the intermediate layer52of insulation.

As alluded to above, the inner portion of the ring14may be characterized as being in the form of a permanently closed, annular clasp that is fixedly mounted onto the outer, annular, peripheral edges of the shells26,28in a manner that holds the shells tightly together. The ring14and/or the ring's clasping feature may be omitted, or provided in any suitable manner. In the first embodiment, the ring14includes an upper ring portion70and a lower ring portion72, and the ring's annular clasping feature is provided by fixedly joining together the upper and lower ring portions70,72so that outwardly extending annular flanges of the shells26,28are pinched between inwardly extending annular flanges of the upper and lower ring portions70,72.

The upper and lower ring portions70,72may be joined together in any suitable manner, such as at an annular connection78between a lower annular surface of the upper ring portion70and an upper annular surface of the lower ring portion72. The annular connection78between the upper and lower ring portions70,72may be formed in any suitable manner. For example, the annular connection78between the upper and lower ring portions70,72may be formed in a leakproof manner by plastic welding, fusing or heat sealing the respective annular surfaces of the upper and lower ring portions together. Suitable methods and apparatus for forming the annular connection78between the respective annular surfaces of the upper and lower ring portions70,72may be available from Emabond Solutions of Norwood, NJ.

Seals between the outwardly extending annular flanges of the shells26,28and the inwardly extending annular flanges of the ring portions70,72may be enhanced by and/or at least partially provided by gaskets, or any other suitable sealing features, in any suitable configuration. More specifically, an upper O-ring84is positioned in an annular channel defined in the outwardly extending annular flange of the upper shell26, and the upper O-ring is compressed between an annular lower wall of the upper shell's channel and an annular lower surface of the inwardly extending annular flange of the upper ring portion70. Somewhat similarly, a lower O-ring88is positioned in an annular channel defined in the inwardly extending annular flange of the lower ring portion72, and the lower O-ring is compressed between an annular lower wall of the lower ring portion's channel and an annular lower surface of the outwardly extending annular flange of the lower shell28.

Optionally, the lower shell28defines a central opening to the inner chamber44, and a spring-loaded pressure relief valve92is mounted to the lower shell for maintaining the central opening in a sealed closed configuration, except that the pressure relief valve is operative for temporarily opening the central opening and thereby venting the inner chamber in response a predetermined differential pressure between the ambient environment and the atmosphere in the inner chamber. More specifically, the opening to the inner chamber44may be at least partially defined by, or associated with, a valve seat, and a valve disk of the pressure relief valve92is typically urged and sealed against the valve seat by one or more springs. The valve disk may be temporarily pushed off of the valve seat, for venting the inner chamber44, in response to any predetermined increase in pressure within the inner chamber, such as may occur in response to the metallic disk22being sufficiently heated. An O-ring or any other suitable structure for aiding in the sealing may be mounted to and carried by the valve disk, so that the spring-driven valve disk forces the O-ring, or any other suitable device, against the valve seat. Alternatively, any other suitable type of pressure relieving device may be used, such as, but not limited to, a “membrane” or diaphragm pressure relief valve. Examples of pressure relieving devices are disclosed in U.S. Pat. No. 6,005,233, and the disclosure of this patent is incorporated herein by reference in its entirety.

For the purpose of providing a more specific example, a second embodiment of this disclosure is described in the following, and the second embodiment is identical to the first embodiment, except for being described more specifically in the following; therefore, the same reference numerals are used. In accordance with the second embodiment:the metallic disk22is a porcelain enamel coated metal disk, and more specifically the metallic disk is a carbon metal disk (the metal comprises carbon as an alloying element) with a porcelain enamel coating;each of the upper and lower shells26,28is constructed of a high temperature polymer material, more specifically each of the upper and lower shells is constructed of reinforced polymer material, and even more specifically each of the upper and lower shells is constructed of a blend of modified polyphenylene ether (PPE) and polyamide (PA) with 30% glass fill;the lower layer50of insulation is 2 mm thick and impregnated with synthetic amorphous silica so that it is hydrophobic, more specifically the lower layer of insulation is a layer of silica aerogel that is 2 mm thick, and more specifically the lower layer of insulation is a 2 mm thick piece of silica aerogel nanoporous insulation;the intermediate layer52of insulation is 5 mm thick and impregnated with synthetic amorphous silica so that it is hydrophobic, more specifically the intermediate layer of insulation is a layer of silica aerogel that is 5 mm thick, and more specifically the intermediate layer of insulation is a 5 mm thick piece of insulation formed of silica aerogel and reinforced with a non-woven, glass-fiber batting;the upper layer54of buffering material is a high temperature silicone pad that is less than about 0.1 inches thick, more specifically the upper layer of buffering material is a high temperature silicone membrane that is 0.032 inches thick, and more specifically the upper layer of buffering material is a piece of high temperature Shore A silicone that is 0.032 inches thick;each of the O-rings60,84,88may be a nitrile O-ring, or an O-ring constructed of any other suitable material;the washer64is a high temperature silicone washer, more specifically the washer is a high temperature silicone ring that is flat and 0.064 inches thick, and more specifically the washer is a flat piece of high temperature Shore A silicone that is 0.064 inches thick; andeach of the upper and lower ring portions70,72of the ring14is Polypropylene.
Each of the dimensions specified above for the second embodiment may be approximate, such that each of the dimensions specified above for the second embodiment may be preceded by “about”. Similarly, each of the dimensions specified above for the second embodiment may vary within a reasonably suitable range/by a reasonably suitable amount, which may be plus and/or minus 5%, plus and/or minus 10%, plus and/or minus 15%, plus and/or minus 20%, or any other suitable amount.

Reiterating from above, the metallic disk22may be in the form of a metal plate, or more specifically a metal disk, that is coated with porcelain enamel, so that the porcelain enamel coating at least partially encloses, and typically fully encloses, the metal disk. The porcelain enamel coating is schematically illustrated inFIG.2by the relatively thick line defining the periphery of the metallic disk22. The porcelain enamel coating advantageously seeks to cause uniform dissipation of heat from the metallic disk22, and also serves as a protective coating, such as for inhibiting rusting of the metal disk.

Partially reiterating from above and in accordance with one specific example of the second embodiment, each of the upper and lower shells26,28is constructed of polymer material (e.g., a blend of modified polyphenylene ether (PPE) and polyamide (PA) with 30% glass fill) that has a heat deflection temperature of 464° F. when tested with a load of 264 psi. In use, the server10is typically not exposed to a load of 264 psi. In a first example of operation of a specific version of the server10of the second embodiment in which each of the upper and lower shells26,28is constructed of polymer material (e.g., a blend of modified polyphenylene ether (PPE) and polyamide (PA) with 30% glass fill) having a heat deflection temperature of 464° F. when tested with a load of 264 psi, the porcelain enamel coated, carbon metal disk22reached a peak temperature of 665° F. in response to being inductively heated by the activator5(FIG.3) for a period of twelve seconds, and the upper layer of buffering material54(in the form of pad of high temperature Shore A silicone having a thickness of 0.032 inches) had a momentary peak operating temperature of 600° F. in response to the heating of metal disk22.

In a second example of operation of the above-described specific version of the server10, the metal disk22reached a peak temperature of 630° F. at the end of being inductively heated by the activator5(FIG.3); at a distance of 0.080 inches into the upper shell26, the upper shell reached a maximum temperature of 492° F. (e.g., core temperature of the upper shell26); and the buffering material54reached a temperature of 570° F. That is, the metal disk22was heated by electromagnetic induction to a first temperature (e.g., 630° F.) that is greater than the heat deflection temperature of the body (e.g., the heat deflection temperature of the upper shell26), and at least a portion of the body (e.g., at least a portion of the upper shell26) was heated by conduction by way of the buffering material54to a second temperature (e.g., 492° F.) that is greater than the heat deflection temperature of the body (e.g., the heat deflection temperature of the upper shell26). The second temperature (e.g., 492° F.) is less than the first temperature (e.g., 630° F.) by 138° F., or more generally by about 138° F. In the second example, the metal disk22was at a temperature of 160° F. at the beginning of the heating cycle, so that the second example simulates the server10being misused, since the metal disk may typically be at ambient temperature at the beginning of a heating cycle.

In each of the first and second examples presented above, the values may be considered to be approximate. The temperatures will vary because, for example, the performance of the servers10may vary slightly from server to server, and the performance of the activators5may vary slightly from activator to activator.

In accordance with a more general example of the second embodiment, the buffering material54is adapted for providing predetermined conductive heat transfer from the metallic disk22to the upper shell26so that the temperature of at least a portion of the upper shell becomes greater than the heat deflection temperature of the upper shell in response to the metal disk being heated by the activator5/electromagnetic induction to a temperature greater than the heat deflection temperature of the upper shell. As a more specific example, the heat deflection temperature of the upper shell26may be about 464° F. when tested with a load of 264 psi, the server10uniformly/as a whole may be at about ambient room temperature (e.g., about 75° F.) prior to being inductively heated by the activator5, the metal disk22may reach a peak temperature in a range of from about 580° F. to about 665° F. in response to being inductively heated by the activator5, and a portion of the upper shell26may reach a peak temperature in a range of from about 460° F. to about 525° F. in response to conductive heat flow (e.g., heat flux) from the metal disk22, through the layer54of buffering material, to the upper shell26. As a more general example, the heat deflection temperature of a portion of the upper shell26may be from about 417° F. to about 511° F., the server10uniformly/as a whole may be at about ambient temperature (e.g., about 75° F.) to about 100° F. prior to being inductively heated by the activator5, the metal disk22may reach a peak temperature in a range of from about 522° F. to about 700° F. in response to being inductively heated by the activator5, and a portion of the upper shell26may reach a peak temperature in a range of from about 414° F. to about 576° F. in response to conductive heat flow (e.g., heat flux) from the metal disk22, through the layer54of buffering material, to the upper shell26. When the server10is operated as discussed above, the peak temperature of the upper shell26, which is above the heat deflection temperature of the upper shell, may be up to about 280° F. less than the peak temperature the metal disk22; or the peak temperature of the upper shell26, which is above the heat deflection temperature of the upper shell, may be less than the peak temperature the metal disk22in a range of from about 55° F. to about 205° F., in a range of from about 108° F. to about 156° F., or a range of from about 120° F. to about 140° F. When the server10is operated as discussed above, the peak temperature of the metal disk22may be more than 81° F., 108° F., 120° F., 140° F., 156° F. or 205° F. hotter than the peak temperature of the upper shell26and/or the peak temperature of the metal disk22may be up to about 310° F. hotter than the peak temperature of the upper shell26.

In an exemplary method of using the server10, the metal disk22is heated by the activator5to greater than the heat deflection temperature of the shells26,28, and then the dish6(FIG.3), which is at about ambient room temperature (e.g., about 75° F.) is placed on the server10as shown inFIG.3. The food7(FIG.3) may be placed on the dish6at any suitable time, such as prior to the dish being placed upon the server10. For example, the food7may weigh about twelve to fifteen ounces, and may be at about 165° F. when it is placed on the dish. The dish6with the food7thereon may be quickly placed upon the server10, so that the dish is only slightly heated by the food prior to the dish being placed on the server. Accordingly, the dish6may be referred to as being at about ambient room temperature after the dish is slightly heated by the food7. The server10may provide sufficient heat energy to heat the dish and the food so that the food is above about 140° F. after an hour of sitting on the dish that is sitting upon the server10. That is, in the exemplary method of this disclosure, the washed dish6does not have to be preheated prior to placing the food7thereon, because the server10provides sufficient heat energy to provide the desired result without preheating the dish, wherein the desired result comprises the food having a serving temperature of at least 140° F. after one hour. That is and in accordance with one aspect of this disclosure, the server10is constructed to control the direction and rate of heat transfer to facilitate the exemplary method of this disclosure. As mentioned above, typically the dish6and food7are covered with the insulated cover8from shortly after the point in time at which the dish with food is placed upon the server10to shortly before the point in time at which the food is to be consumed. Accordingly, the insulated cover8and the server10may be cooperative for providing the above-discussed functionalities.

In contrast to the exemplary method of this disclosure, it is conventional for a dish that has been washed to thereafter be preheated to at least 165° F. in a dish heater, and then for the food at a temperature of at 165° F. to be placed on the preheated dish prior to placing the dish on an induction-based heat retentive server. It can be disadvantageous to preheat numerous dishes, because doing so requires space and energy. Having to preheat numerous dishes may also be a safety hazard, since foodservice operators may get burned by touching the dish heaters in certain spots.

In the exemplary method of this disclosure, any conventional dish heater (not shown) that is proximate the system of this disclosure may be bypassed (e.g., the dish6is not heated) between the washing of the dish6in a conventional manner and the placing of the dish upon the server10. Notwithstanding, this disclosure is not limited to requiring bypassing of any dish heater/the dish6may alternatively be heated by a dish heater prior to placing the dish upon the server10.

The activator5(e.g., its induction coil(s) and generator(s)) are typically configured to be powerful enough to provide the values discussed above. For example, the activator5may include a guide or receptacle for receiving the server10, and the activator may provide a power output of 10 kilowatts for twelve seconds while the server is properly positioned in the receptacle, so that the metallic disk22of the server is heated by way of electromagnetic induction. The activator5may provide the power output in response to the server10initially engaging an activation switch. The activation switch may be positioned in the receptacle so that the activation switch is engaged by the server10when the server is properly positioned in the receptacle. For cooling the electronics within the activator5, the rear wall of the activator may be vented (e.g., louvered), and standoff structure(s) such as projections, brackets or any other suitable spacers may project from proximate the rear wall in a manner that seeks to prevent the vents in the rear wall from becoming obstructed. Any other suitable activator5may be used.

In the foregoing, examples are provided of features that are cooperative for providing predetermined conductive heat transfer. However, it may be possible to use a lesser number of the subject features and/or the subject feature(s) in different configurations to provide the predetermined conductive heat transfer, or the like; therefore, the provision of specific examples herein is not intended to limit the scope of this disclosure.

Whereas the disk assembly18and the ring14are often round in shape, they may be shaped differently, so that the server is oblong or in the shape of a quadrilateral, such as a parallelogram, or in any other suitable shape. In addition, the obliqueness and/or height of the ring14relative to the disk assembly18may vary, such as by the ring being more shallow and/or more upright, and the ring may be otherwise reduced in size or even omitted. As another example, one or more of the disk assemblies may be incorporated into a single tray.

The above examples are in no way intended to limit the scope of the present invention. It will be understood by those skilled in the art that while the present disclosure has been discussed above with reference to exemplary embodiments, various additions, modifications and changes can be made thereto without departing from the spirit and scope of the invention as set forth in the claims.