US2396455A - Food drier - Google Patents

Description

March 12;, 1946. 1-; c. BOOTH V FOOD DRIER Filed Ju1y 28, 1943 INVENTOR. fie! 6. oar/1,

Patented Mar. 12, 1946 2,396,455 FOOD DRIER Earl C. Booth, Columbus, Ind., assignor to Noblitt-Sparks Industries, Inc., Columbus, Ind., a corporation of Indiana Application July 28, 1943, Serial No. 496,500

' 7 Claims.

This invention relates to a drier suitable for use in the drying of fruits and vegetables or other foods, and more particularly to a drier adapted for domestic use. It is the object of my inven tion to produce a drier of the type indicated which will be efiicient in use and which can be simply and economically manufactured. Another object of my invention is to produce a drier in which the drying operation can be readily followed and controlled.

In carrying out the above objects, I form a drier frame of sheet metal to provide bottom and end walls. Side edges of these walls are equipped with provisions for the reception of panels of glass or other transparent material forming the side walls of the drier. The drier is divided interiorly by an intermediate horizontal partition beneath which is disposed an air-circulating and air-heating means, and the partition is provided near its ends with air-passing openin s. In the upper portion of the drier, above such partition, I provide a removable tray-carrier adapted to support a series of vertically spaced trays upon which the material to be dried is distributed. The tray-carrier is reversible in the drier so as to reverse relatively the direction in which heated air passes over the trays. To control the operation of the drier, it is equipped with a thermometer indicating the temperature of the circulating air and with means for controlling the temperature of the air.

The accompanying drawing illustrates my invention: Fig. l is a side elevation of the drier with the major portion of the side Wall broken away to illustrate the interior construction; Fig. 2 is a vertical transverse section on the line 22 of Fig. 1; Fig. 3 is a fragmental isometric view illustrating a detail of construction; and Fig. 4, is a side elevation of the tray-carrier removed from the drier.

The drier shown in the drawing comprises a bottom wall l and end walls II and I2. Channels l3, adapted slidably to receive panels 14 of glass or other transparent material, extend along the side edges of the bottom and end walls. To stiffen the frame, gusset plates l5 may be secured as by welding to the vertical and horizontal channels l3 at the corners of the bottom wall 10. The bottom wall Ill, end walls II and I2, channels I3, and gusset plates I5 are conveniently all formed of sheet metal.

Extending horizontally across the drier and from one end wall to the other is an intermediate partition l1, also desirably of sheet metal. Adjacent its ends, the partition I1 is provided with openings 18 through which air may flow between the upper and lower portions into which the in terior of the drier is-divided by the partition ll. To stiffen the partition [1, its edge portion may be bent downwardly to form stiffening flanges, and the material of the partition at the edges of the openings I8 may also be bent to form stiffening flanges.

In the space between the bottom wall In and the intermediate partition I1 I provide a heating means, desirably a resistance heating element 25. This. element is conveniently supported on a sheet-metal sub-frame 2|. Also mounted in the space beneath the partition I! is a fan-shroud 22 having a central circular opening within which there is disposed a rotatable fan 23. The latter may be driven by an electric motor 24 supported in any suitable manner from the shroud 22 and from a support 22'. The support 22', shroud 22, and sub-frame 2| desirably extend between the bottoom wall l0 and the partition I! to aid in the support of the latter.

On the inner face of each of the end Walls H and 12 there is provided a box-like structure comprising a top wall 25, an inner wall 25 and side walls 21. Each inner wall 26, from its point of juncture with the associatedtop wall 25, slopes generally downwardly and outwardly, joining and being secured to the associated end wall of the drier at a point about the level'of the horizontal partition I1. Extending between the two top walls 25 along each side of the drier are a pair of brace members 30. Each of these brace members is conveniently formed of sheet-metal and has a vertically extending flange 3| adapted to overlie the outer surface of the associated sidewall panel l4, as will be clear from Fig. 3. At its ends, each of the members 30 has inwardly directed horizontal flanges 32 which overlie and are removably secured to the top walls 25 as by bolts 32'. Between the flanges 32, the member 30 is formed to provide a vertical flange 33 which is spaced'inwardly from the flange 3| to provide a channel within which the upper edge of the sidewall panel I4 is received. The tray-carrier, previously referred to, is received in the drier in the space between the inner walls 26 at the opposite ends thereof. As shown in the drawing, the tray-carrier is formed of sheet metal and comprises a bottom wall 35, side walls 36, and a top Wall 31, all conveniently formed of sheet metal. Each side wall 35 may be provided with a plurality of horizontal rows of openings 36' having horizontal lower edges. The material along the horizontal edges of the openings is bent inwardly of the tray-carrier to form a series of tray-supporting flanges 38 in a manner which will be clear from Fig. 2. The trays 39 supported on the flanges 38 may also be formed of sheet-metal and desirably have foraminous bottoms.

For the purpose of carrying the drier, I may mount on each of the top walls 25 a suitable handle 40. Similar handles 4| may be provided at opposite sides of the top wall 31 of the traycarrier.

For the purpose of adapting the electric motor 24 for connection to supply wires, an electrical attachment plug 50 is provided in the end wall H. A rheostat or other current-controlling element 5|, which may be mounted in the opposite end wall I2, is provided for the purpose of controlling the amount of heat produced by the heating element 20.

In the drying of fruits or other foods, it is 'usually deemed desirable to recirculate aportion of the air in order to avoid excessive heat loss and to replace a portion of the air in order to provide for the carrying away of the moisture removed from the fruit or other food. To efiect the replacement of a portion of the circulating air, I provide the end wall H withan air-admission opening 52 and an air-discharge opening 54, both desirably covered with screens, the opening 53 being located below the partition I! and the opening 54 above it. Opposite the opening 54, the inner wall 26 is provided with an opening 55.

In operation, an extension cord is connected to the attachment plug 50, thus causing the motor 24 to operate and the fan 23 to blow air over the resistance heating element 'toward the end wall I2. The stream of heated air thus produced passes upwardly through Openings l8 in the horizontal partition I! into the space between the end of the tray-carrier and the inner wall 26. Be cause of the slope of the inner wall 26, this space is of gradual decreasing cross-sectional area toward its upper end, thus providing for an even distribution of air among the horizontal passages defined by the vertically spaced trays 39 in the tray-carrier. In accomplishing this purpose, I have found it desirable to choke thespace rather abruptly above the partition l1, thus favoring the supply of air to the lower trays. To this end, the inner wall 36 slopes rather steeply from its upper end to a point about the level of the second tray from the bottom of the tray-carrier and then slopes more gradually toward its point of juncture with the end wall I2. A portion of the air discharged upwardly through the openings 18 will impinge upon the less steeply inclined lower portion of the wall 26 and will be deflected toward the lowermost trays 39. To aid in directing the air discharged from the heating element 29 into the openings I8, I may provide a bafile 56 extending obliquely between the bottom wall 10 and end wall I2, as shown in Fig. 1.

Entering the spaces between the trays in the tray-carrier, the heated air passes from right to left across the fruits, vegetables, or other food, which is distributed in a relatively thin layer on each of the trays 39. A portion of the air passing over the trays will find its way through the openings 55 and 54, and will thus leave the drier to be replaced by air drawn inwardly through the opening 53. Such air as does not escape through the opening 54 after passing over the trays passes downwardly through the openings l8 at the left-hand end of the partition I1 to-the fan, and is recirculated thereby.

A thermometer 68, conveniently mounted on a wall 21 at that end of the drier toward which the fan discharges and so a to be visible through the adjacent transparent side wall 24, is provided in order to indicate the temperature of the air being supplied to the food on the tray 33. By suitable operation of the rheostat or other heating-control element 5!, this ai is maintained at the desired temperature. Approximately half-way through the drying period, Or at more frequent intervals if desired, the tray-carrier is removed from the drier, reversed, and replaced. This effects a more uniform drying action throughout the longitudinal extent of the tray, since it results in the bringing of heated air immediately after it leaves the heating element 20 into contact with the food at each end of the tray. During the drying operation, the contents of the trays are visible at all times through the transparent side walls 14 of the drier and the openings 36 in the side walls of the tray-carrier.

I claim a my invention:

1. A food drier, comprising a casing having an opening in its top, a closure for said opening, a

-' tray-carrier receivable in said opening, said traycarrier having open ends and provisions for. supporting in vertically spaced relation a plurality of trays individually insertable into and removable from said tray-carrier through its open ends, aid tray-carrier having a length and height respectivelyless than the interior length and height of said casing whereby the carrier when in place will be spaced from the ends and bottom of said casing to provide, in co-operation with the spaces between the trays, a circulatory path for air, and means located in said casing below said carrier when it is in place in the casing for heating air and circulating it over such circulatory path, said casing being provided with air-inlet and airoutlet openings communicating with said circulatory path at spaced points therealong.

2. A food drier, comprising a casing having an opening in its top, a; closure for said opening, a tray-carrier receivable in said opening, said traycarrier having open end and provisions i or supporting in vertically spaced relation a plurality of trays individually insertable into and removable from saidtray-carrier through its open ends, said tray-carrier having a length and height -espectively less than the interior length and height of said casing whereby the carrier when in place will be spaced from the ends and bottom of said casing to provide an air-circulating path comprising, in succession, the space between the carrier and the casing-bottom, one of the spaces between an end of the carrier and the adjacent end of the casing, the spaces between the trays, and the space between th other endof the carrier and'the adjacent end of the casing, and means located in said casing for heating air and circulating it over such air-circulating path, said casing being provided with air-inlet and airoutlet openings communicating with such path at spaced points therealong.

3. The invention set forth in claim 2 with the addition that said carrier and opening are so shaped that the carrier is receivable in the ca$- ing alternatively in either of two positions spaced about the vertical.

4. The invention set forth in claim 1 with the addition of means located between said carrier and an end of the casing for deflecting toward the lowermost of said trays air discharged from saldheating and circulating means.

5. The invention set forth in claim 1 with the addition of means located between said carrier and an end of the casing for defining in co-operation with the adjacent end of th carrier an air passage of decreasing cross-sectional area toward its upper end.

6. The invention set forth in claim 2 with the addition that said carrier has side Walls provided with openings, said casing having side walls at least one of which is transparent over an area substantially coextensive with the adjacent side wall of said carrier.

7. The invention set forth in claim 2 with the addition that said casing is provided with air inlet and discharge openings.

EARL C. BOOTH.

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