US2836478A

US2836478A - Heat retaining cover

Info

Publication number: US2836478A
Application number: US527220A
Authority: US
Inventors: Miller Grace
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-08-09
Filing date: 1955-08-09
Publication date: 1958-05-27
Anticipated expiration: 1975-05-27

Description

May 27, 1958 G. MBLLER HEAT RETAINING COVER Filed Aug. 9, 1955 GRACE J. MILLER HEAT RETAINING COVER Grace Miller, Tallahassee, Fla.

Application August 9, 1955, Serial No. 527,220

1 Claim. (Cl. S12-284) This invention relates to covers for retaining heat, particularly those for placing over food on a plate which is to be transported an appreciable distance from the kitchen. It will have particular usefulness in hospital service where the equipment receives rough treatment in the hands of poorly paid employees.

A11 important object of the invention is to provide a double-walled cover of heat-retaining type which has an inside surface free from cracks or crevices which could collect bacteria and an outside surface minimizing passage of heat from the space between the walls.

A still further object of the invention is to provide a heat-retaining air space type cover highly suitable for hospital use in which the two main parts can readily be separated for separate sterilization and which, if the outer plastic cover should be broken, it can readily be replaced for use with the old inner metal ceiling or dome of the cover.

ln the drawings:

Figure l is a central vertical section.

Figure 2 is an enlarged fragmentary sectional view of the peripheral joint.

Figure 3 is a modification.

The cover consists of two spaced walls, each of a single piece of material of substantially uniform thickness, and means for detachably lconnecting the two parts together so as to provide a heat insulating space between the two walls or domes, the securing means preferably being operable without any tools and the entire cover being so made that there will be no crevices in which food particles might be caught, as the device, although having general use, is designed primarily for service in hospitals where it is important that the cover be very easy to sterilize and where, as here, the outer cover is relatively breakable with respect to the inner cover so that a new cover can readily be assembled with the other portions. To this end an inner dome is formed of a metal which could be Monel metal, stainless steel, etc., but is preferably aluminum of a rather high density. This inner shell can be of any normal shape commonly used for double-walled covers of this type. Itis my preference that the central top surface 11 be very slightly curved on an extremely large spherical radins, although actually it can be perfectly at. Likewise, the side walls 12 would follow a curved formation if the top were spherical, but for ease of manufacturing and for obtaining maximum space within the cover the side wall is made substantially a cylinder as illustrated. Whatever the shape of the metal of the top and the sides, the upper circular junction as at 14 should be a smooth curve.

The outer wall or dome corresponds generally in shape to the inside dome 10 but to increase the space between the two walls of the cover I prefer that the distance apart of the two walls at the vertical axis shall be greater than the space 2 1 near the circular top edge of the cover, this space 21 being approximately the same transverse dimension as the space 22 along the sloping or vertates Patent 2,835,478 Fatented May 27, 1958 tical sides of the cover between the two walls. lt is quite important to make the walls of the cover of qulte different materials and, hence, the outer dome 20 is preferably of a plastic material having a high heat insulating value, preferably one that will take a smooth nish on the outside and thick enough to take quite a bit of abuse without damage. The inside surface 15 of the inner dome is preferably highly polished, mirrored as often expressed, as this will relect heat back to the food 30 on plate 31.

As a preferable means for joining the two domes to-V gether, a screw 33 is permanently carried by the inner dome 10 and extends loosely through the plastic outer dome 20. The handle 34 of the cover is of either metal or plastic and is internally threaded as at 35 to serve as a nut to bring the two domes into rm contact at the junction of their lower peripheral edges and yet be quickly removable without tools for separate sterilization of the two parts whenever that might be required or for replacement of a broken outer cover.

This peripheral joint at the bottom of the cover is of great importance. It is my preference that the inner metal dome 10 shall curve as at 16, ending in a cylindrical face 17 even with the outer surface 24 of the outer dome. By having the metal project to the margin of the outer cover, we will lose a very slight amount of heat to the atmosphere, but in a device of this kind durability is much more of a concern than the very slight loss in heat. By having the metal edge 17 below the outer dome, the latter is given a very much greater life as the blows that normally destroy an outer cover are received at the bottom circular edge of the cover and such blows `.vill all be taken by the metal and not by the more easily damaged plastic shell or dome.

The plastic outer dome 20 is molded in such fashion as to provide an enlargement 25 having at its bottom a at annular shoulder 26 which will be in light contact with a similar annular shoulder 18 on the metal inner dome when the parts are assembled. From the inner edge of the shoulder to the outside margin of the cover both domes have matching curves 27 which iirst make contact as the handle 34 is screwed down, the at

co-planar surfaces

18 and 26 forming a stop so that when these at surfaces 1S and 26 are in firm contact the outer

cylindrical walls

17 and 24 are in perfect registry. It will be noted that the inner face of the cover that could get in contact with the food is a smooth, unbroken surface having no joint or crack of any kind, the screw 33 being secured to the upper surface of the dome and not extending down as far as the mirrored surface 15.

In the modification shown in Figure 3, the outer plastic shell is much the same as before but its skirt 40 directly touches the serving dish 31 and the metallic portion of the cover is quite restricted in size, consisting of an outer metal disk 41 and an inner metal disk 42, the latter being the bottom wall of the upper air space of the cover. Each of the

plates

41 and 42 are highly polished or mirrored on their lower surfaces and they are spaced by a separating ring 45 which makes a snug t with the skirt 40 which is preferably conical. The mirrored surface of disk 42 reects heat downwardly toward the food and this surface is not aected by the steam which would collect on the bottom surface of plate 41. The screw 33 is secured to both disks. In using this modification, it is proposed to use a strong, tough plastic shell.

What I claim is:

A double-walled heat retaining cover for food served on a plate in which the two walls are normally secured together to form a single unit, said cover having an outer wall of a heat insulating plastic having the general shape of a dome with a roof and a skirt, the outer surface of said cover being a smoothly curved surface of revolution ending inV a circular lower edge, and the inner wall of the cover comprises a metal member ittngV the outer-f dome in a zoneV of contact bounded by a surface of revolution and having a mirrored 4surface, parallel to the plane of the open lower circular edge of the cover to/reect heat;

back'to the food on; the plate, said metal innerY wall having a peripheral edge which vunderlies` the circular Vlower edge oijthe plasticouter wall, whereby-when the walls are as-` sembled, the plasticouter wall is protected against breakage from a blow onrthe lower outside edge of the cover by Y the underlying metal edge, and readily separable threaded vapor from hot food'witbin Ythe cover being smooth land unbroken, thus vavoiding any possibility of lcrevices that might collect` bacteria, so that the cover is particularly suitable for hospitaly service.

References Cited in the le of this patent UN'ITED STATES PA'EN'I'SV 24,636 Smith July 5,y 1859 Pecor Feb. 5, Sperry Apr. '26, Owens Aug. 15, Oskarnp Feb. 22, Round June 1Y0, Jackson Apr. 24, Montgomery Apr. 24, Werber et alf.y Oct.`2, Bolen Aug. 15, Maersch July 9, Petersonv Sept. 17,

t Montgomery May 25,v Maersch Feb. 10,

FOREIGN PATENTSl Y,

Great Britain Apr.'21, Great Britain Mayl 9,Y

Germany Nov. k5,