US20070131698A1

US20070131698A1 - Thermal food tray

Info

Publication number: US20070131698A1
Application number: US11/638,184
Authority: US
Inventors: Keith Antal
Original assignee: Sonoco Development Inc
Current assignee: Sonoco Development Inc
Priority date: 2005-12-13
Filing date: 2006-12-13
Publication date: 2007-06-14
Also published as: WO2007070615A3; WO2007070615A2; EP1959801A2; JP2009519108A

Abstract

A tray for handling food in a warming oven comprises a dish portion a rim portion and a gasket portion. The dish portion is constructed from a first material and has a base portion adapted for handling of food products. The dish also has a wall portion surrounding the entirety of the base portion and extending therefrom. The wall portion has a closed end connected to the base portion and an open end disposed away from the base portion. The rim portion is constructed from a second material and extends generally parallel to the wall portion, around the perimeter of the dish portion. The rim portion has an attached end adapted for compressive engagement with the open end of the wall and a free end adapted to facilitate handling of the tray. The gasket is compressively disposed between the dish and the rim and adapted to restrict the movement of the dish away from the rim.

Description

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/749,931, filed Dec. 13, 2005.

FIELD OF THE INVENTION

The invention relates to apparatus for keeping food warm between the time of preparation and service.

BACKGROUND

Warming ovens are used in the food service industry to keep food warm between the time of preparation and the time of service. Trays constructed of plastic are presently used because of their ease of handling, and their durability. When kept in the warming oven, however, it is sometimes preferable that food is in contact with metal surfaces, such as aluminum or stainless steel, rather than plastic or other non-metal materials. Metals, however, are subject to deformation and the development of sharp edges because of wear and tear. Further, when stored at elevated temperature conditions, metal tends to become hot to the touch, thereby making the tray difficult to handle. Accordingly, it is desirable to produce a tray that has the food storage characteristics of metal while having properties of materials that are easier to handle at elevated temperature conditions.

SUMMARY OF THE INVENTION

This invention relates to apparatus for keeping food warm between the time of preparation and service. Specifically, the invention relates to a tray for retaining food products in warming ovens or other environmentally controlled devices.
One aspect of the present invention is a tray having a dish portion, a rim portion and a gasket portion. The dish is constructed from a first material and includes a base portion adapted for handling food products. The dish also includes a wall portion surrounding the entirety of the base portion and extending upwardly therefrom to define a retaining area. The retaining area is closed by the base portion at the bottom end of the wall and opens away from the base portion at the upper end of the wall. The rim is constructed from a second material and has an inner lip that extends generally parallel to the wall portion of the dish. The inner lip is secured around the perimeter of the wall of the dish. The rim is attached to the wall by a compressive engagement. The rim also has a free end for handling of the tray. The gasket is compressively disposed in the lip and forms the compressive bond between the dish and the rim.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in the drawings a form, which is presently preferred; it being understood, that this invention is not limited to the precise arrangements and instrumentalities shown.
FIG. 1 is a perspective view of a tray according to an embodiment of the present invention.
FIG. 2 is a second perspective view of the tray shown in FIG. 1.
FIG. 3 is a cross-sectional view of the tray shown in FIG. 1.
FIG. 4 is a cross-sectional view of a portion of the tray shown in FIG. 1, detailing the attachment of a dish to a rim.
FIG. 5 is a cross-sectional view of a tray according to an embodiment of the present invention.
FIG. 6 is a cross-sectional and perspective view of the tray shown in FIG. 4.
FIG. 7 is a cross-sectional view of a gasket for use in a tray embodiment of the present invention.
FIG. 8 is a perspective view of the gasket shown in FIG. 6.
FIG. 9 is a cross-sectional view of a portion of the tray shown in FIG. 4.
FIG. 10 is a side elevational view of tray shown mounted within a warming oven.

DETAILED DESCRIPTION OF THE DRAWINGS

It will be appreciated that the following description is intended to refer to specific embodiments of the invention selected for illustration in the drawings and is not intended to define or limit the invention, other than in the appended claims.
In the Figures, in which like reference numerals indicate like elements, there is shown an embodiment of a tray for use in warming ovens, such as those commonly used in fast food restaurants. The tray, which is identified generally by the numeral 10, may be used to store food in an orderly and easily accessible manner while the food waits in a warming oven (not shown) or other environmental control device prior to service, further preparation or processing. For purposes of this disclosure, the directions up and down, will refer respectively to those directions when viewed in FIG. 1.
The warming oven may be used in a fast food restaurant to hold prepared food between the time of preparation and the time of serving. It is preferable that the warming oven keep the food in a ready-to-eat state. Temperatures inside the warming oven may reach levels above 180 degrees Fahrenheit. It is also desirable to regulate the humidity within the oven to ensure that the food does not become dried out or soggy. A tray for use in such ovens must be constructed from materials that will withstand the conditions within the oven, as well as other storage and cleaning conditions. Further, because the tray is used in the food service industry, it is preferable that the materials and construction meet the guidelines of the National Sanitation Foundation (NSF) for such apparatus.
Referring to FIGS. 1-3, the tray 10 as illustrated includes a dish portion 20, a rim portion 40 and a gasket 60. The gasket 60 is disposed between the dish 20 and the rim 40 for compressive engagement of the dish 20 and rim 40 to form the tray 10.
The dish 20 includes a generally rectangular base 22 defining the bottom of the tray 10. Preferably, the length of the tray 10 is about two feet and the width W is sufficient to accommodate the food item that is to be contained therein, such as a hamburger patty. The base 22 is generally flat and has an inner surface 30 and an outer surface 32. A sidewall 24 extends upwardly from the perimeter of the base 22. The sidewall 24 and the base 22 are preferably of unitary construction, and define the retaining area of the dish 20. One or more ridges 26 may be provided longitudinally along the base 22. The ridges 26 are generally raised above the remainder of the inner surface 30 and support the food (not shown) above the remainder of the inner surface 30 of the base 22, thereby forming a passageway under the food for circulation of heated air or allow for the drainage of juices from the food. Those skilled in the art will recognize that although longitudinal ridges 26 are shown, lateral ridges or some pattern or ridges, bumps or other features may be disposed on the base without departing from the scope of the present invention.
The wall 24 preferably surrounds the base portion 22. The joint between the wall 24 and the base 22 is curved. The retaining area is closed by the base 22 at the bottom and is open at the upper end 24 b along the top edge of the wall 24. As illustrated, the wall 24 extends generally perpendicular to the base 22. However, the wall may also extend outwardly and upwardly from the base, or have other features without departing from the scope of the present invention.
The rim portion 40 extends around the perimeter of the dish 20. Preferably, the rim 40 comprises a vertical section 42 having an upper portion 43 and a lower portion 44. The lower portion 44 has an inner wall 44 a and an outer wall 44 b. A retaining channel 45 (FIG. 4) is preferably disposed between the inner and outer walls 44 a, 44 b. As will be described in further detail below, the retaining cavity 45 is adapted to receive the open end 24 b of the wall 24 for securing the rim 40 to the dish 20.
Referring now to FIGS. 1-6, the upper portion 43 of the vertical section 42 of the rim 40 extends upwardly from the lower portion 44. A plurality of apertures 47 may be provided through the upper portion 43 to facilitate circulation of air into the tray 10. Outer rim 48 extends outwardly along the longitudinal sides of the rim 40. The outer rims 48 preferably have a generally arcuate cross section with a rounded convex top surface 48 a and a generally concave bottom surface 48 b. In some examples of the tray 10, the bottom surface 48 b may be sized to facilitate the mounting of the tray 10 on rails disposed within the oven. Those skilled in the art will recognize that a variety of configurations may be used to facilitate mounting of the tray in an oven without departing from the scope of the present invention.
Mounting end portions 52 are preferably disposed at longitudinal ends of the rim 40. The mounting ends 52, like the outer rims 48 preferably facilitate the mounting of the tray 10 inside of a warming oven. The mounting ends 52 extend across the width W of the tray 10 and have downwardly depending corner portions 53. The corner portions 53 are hollow, and are open on top to facilitate grasping the trays 10. Slots 54 are also provided in the mounting ends 52 and define a resilient tab for engagement of the tray 10 by an oven structure (not shown), for retention of the tray 10 in the oven.
A gasket 60 is disposed between the dish 20 and the rim 40 and adapted to resiliently secure the rim 40 to the dish 20. As best seen in FIGS. 3-9, the gasket 60 preferably has an inverted, generally U-shaped cross section with an upper portion 62 and outer walls 64 extending downwardly therefrom. Internal ribs 66 extend inwardly and upwardly into the central portion of the U-shape. The internal ribs 66 facilitate the insertion of the upper end 24 b of the wall 24 into the gasket 60 and then resist the withdrawal of the wall 24 therefrom. Outer ribs 68 are disposed on the outer surface of the gasket 60. The outer ribs 68 preferably extend outwardly and downwardly from the gasket wall in a manner that facilitates the insertion of the gasket 60 into the retaining cavity 45 formed by the inner and outer walls 44 a, 44 b of the rim 40 and restricts the movement of the gasket 60 therefrom.
During assembly, the gasket 60 is disposed about the dish portion 20 by inserting the open end 24 b of the wall 24 between the outer walls 64 of the gasket 60. One wall 64 is preferably disposed on the inside of the dish 20, while a second wall 64 is preferably disposed on an outside of the dish 20. The inner ribs 66 preferably engage the open end 24 b and are pressed upwardly as the open end 24 b is slid into the gasket 60. The angle of the inner ribs 66 preferably restricts the movement of the gasket 60 away from the dish 20, once the open end 24 b is inserted in the gasket 60. It is preferable that the engagement between the gasket 60 and the dish 20 is tight, providing a snug fit between the two pieces 60, 20. The wall 24 of the dish 20 may also be textured, bent, curled or the like to increase frictional engagement with the gasket 60 and to resist the disassembly of the tray 10.
After attachment of the gasket 60 to the dish 20, the gasket 60 is then inserted into the retaining cavity 45 of the rim 40. The outer ribs 68 are shown as angled to facilitate the insertion of the gasket 60 into the cavity 45 by allowing the inner and outer walls 44 a, 44 b to slide along the ribs 68 while pushing them towards the gasket 60. The ribs 68 may take other forms, such as being straight or including a chamfer, so as to increase retention of the gasket 60 in the cavity 45. Like the inner ribs 66, the angle of the outer ribs 68 restricts the movement of the gasket 60 out of the cavity 45 once the gasket 60 is inserted therein. The cavity 45 is preferably sized to compress the gasket 60 between the first and second walls 44 a, 44 b and the open end 24 b of the dish wall 24. The deformation of the ribs 66, 68 and the compressable nature of the material of the gasket 60 allows the gasket 60 to resiliently retain the rim and the dish together. It is preferable that the gasket 60 allow for thermal expansion of the dish 20 and the rim 40, while still maintaining a seal between the two parts 20, 40.
The dish 20 is preferably constructed from a metal. Examples of such metals are stainless steel, titanium and aluminum, with aluminum being the preferred material. It is also preferable that the rim 40 be constructed of a plastic material of the type generally adapted to be used in temperature and variable humidity conditions of a food preparation and warming oven, without corrosion, deformation or reaction with surrounding materials. The gasket 60 is preferably constructed from a material that maintains a seal between the dish 20 and the rim 40 in heated conditions, as well as at room temperature and in colder environments, such as refrigerators or freezers. The gasket 60 is preferably adapted to accommodate a ratio of thermal expansion of 10 to 1 between the plastic of the rim 40 and the metal of the dish 20, respectively. In other words, the plastic of the rim 40 may expand up to 10 times more than the metal of the dish 20 at certain temperatures. Higher ratios of expansion are also contemplated without departing from the scope of the present invention. The gasket 60 should maintain a seal after repeated use and cleaning of the tray. Such a material should also be resistant to corrosion and hardening after exposure to chemicals used in cleaning, as well as exposure to food products in a variety of temperature and humidity conditions. As mentioned above, it is preferable that the materials and construction used meet the NSF guidelines for food service devices.
In a preferred embodiment of the tray 10, the seal is maintained between the dish 20 and the rim 40 in a variety of thermal states. For example, in a first state, such as when the tray is inside of the oven and maintained at an elevated temperature, the rim 40 may be expanded in such a way that the wall 64 of the gasket adjacent to wall 44 a of the rim 40 experiences an increase in compression between the wall 24 of the dish 20 and the inner wall 44 a. The compression of the inside gasket wall 64 occurs because the plastic material of the rim 40 will normally expand at a greater rate or amount than the metal of the dish 20 when both are heated. Correspondingly, in a second state, the seal is maintained by the compression of the wall 64 of the gasket 60 between the outer wall 44 b of the rim 40 and the wall 24 of the dish 20. This second state of thermal expansion occurs at a temperature that is cooler than that discussed above for the first state, such as when the tray is at a temperature that is cooler than ambient room temperature. It is also preferable that during the transition between the first and second states of thermal expansion, the seal is maintained by the compression of at gasket between the first and second walls 44 a, 44 b and the dish 20.
Referring now to FIG. 10, in use, the tray 10 is placed within an oven 70. The oven 70 is a traditional warming oven with front and rear doors 72, 74. While the tray 10 is within the oven 70, heat is readily transferred through the metal dish portion 20, and is less readily transferred through the rim 40. In instances where food is prepared on one side of the oven 70 and served (or further prepared) on the other side of the oven 70, the tray 10 may inserted through the first door 72 and slid across the bottom 76 of the oven 70. The tray 10 may then be removed using the second door 74. Alternatively, the slots 54 (not shown in FIG. 10) facilitate the engagement of the tray 10 with a corresponding oven structure (not shown), indicating to a user that the tray 10 is in its proper position within the oven 70.
While a press fit between the dish 20 and the rim 40, with the gasket 60 disposed therebetween, is the preferred method of construction, other methods may be used contemplated without departing from the scope of the present invention. Regardless of the assembly method, it is desirable that a gasket is utilized between the dish and the rim to simplify the manufacturing process, to maintain a seal and to secure the dish to the rim.
A variety of modifications to the embodiments described will be apparent to those skilled in the art from the disclosure provided herein. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims

1. A tray for handling food in a warming oven comprising:

a dish, constructed from a first material, having

a base portion adapted for handling of food products, and

a wall portion surrounding the entirety of the base portion and extending upwardly therefrom, the wall portion having a lower edge connected to the base portion and an upper edge disposed away from the base portion;

a rim, constructed from a second material, the rim having a lower edge adapted for engagement with the open end of the wall portion and a free end adapted to facilitate handling of the tray; and

a gasket compressively disposed between the dish and the rim and adapted to resiliently secure the dish and the rim.

2. The tray according to claim 1, wherein the first material is a metal.

3. The tray according to claim 1, wherein the second material is a plastic.

4. The tray according to claim 1, wherein the base portion comprises at least one ridge extending along at least a portion thereof.

5. The tray according to claim 1, the tray further comprising a first end and a second end disposed longitudinally away from the first end, each of the first and second ends having a gripping tab portion extending longitudinally therefrom.

6. The tray according to claim 1, the free end of the rim having at least one mounting tab extending along a lateral portion thereof.

7. The tray according to claim 1, wherein one of the lower edge of the rim and the upper edge of the dish has a first wall, a second wall, and an attachment cavity disposed between the first and second walls.

8. The tray according to claim 1, wherein the gasket has a generally U-shaped cross-sectional profile, having an inner portion and an outer portion, wherein each portion is adapted for engagement with one of the upper edge of the wall portion of the dish and the lower edge of the rim.

9. The tray according to claim 8, the gasket further comprising at least one retaining rib extending therefrom for engagement with one of the upper edge of the wall portion of the dish and the lower edge of the rim.

10. The tray according to claim 9, wherein the retaining rib is angled to facilitate movement of the gasket with respect to a portion of the tray in a first direction and restrict the movement of the gasket with respect to said portion in an opposing second direction.

11. The tray according to claim 8, wherein the upper edge of the wall of the dish is insertable into the inner portion of the gasket.

12. The tray according to claim 11, wherein the outer portion of the gasket is compressively insertable into the attachment cavity of the rim, for retainment therein.

13. The tray according to claim 1, wherein the wall portion is generally perpendicular to the base portion.

14. A tray for handling food in a warming oven comprising:

a dish constructed from a first material having a peripheral wall with inner and outer faces;

a rim constructed from a second material having a peripheral cavity defined by inner and outer rim walls, the second material having a greater coefficient of thermal expansion than the first material; and

a generally U-shaped gasket constructed from a resilient material, having a first gasket portion and a second gasket portion disposed on the peripheral wall with the first gasket portion disposed adjacent to the inner face and the second gasket portion disposed adjacent to the outer face;

wherein the rim disposed about the gasket and the peripheral wall with the inner rim wall disposed proximate the first gasket portion and the outer rim wall disposed proximate the second gasket portion; and

wherein a seal is formed between the inner wall and the inner face of the peripheral wall, in conjunction with or separately from the outer wall and the outer face of the peripheral wall, due to compression of the first and second gasket portions therebetween and at various states of thermal expansion of the materials.