Apparatus for treating foodstuffs

Jan, 24, 1939.

o. h. biggs 2,145,196

APPARATUS FOR TREATING FOODSTUFFS /

Original Filed Nov. 16, 1933

DURATION

<img file="US2145196A_D0001.tif" />

Patented Jan. 24, 1939

2,145,196

UNITED STATES PATENT OFFICE

2445,196 APPARATUS FOR TREATING FOODSTUFFS Orrick Howard Biggs, Beverly, Mass., assignor to Hygrade Sylvania Corporation, Salem, Mass., a corporation of Massachusetts

Original application November 16, 1933, Serial No. 698,265. Divided and this application June 26, 1934, Serial No. 732,431

Claims.

This invention relates to methods and apparatus for treating materials by radiation and with particularity to an improved form of sterilizing chamber.

δ An object of the invention is to provide a sterilizing chamber particularly suited to the housing of foods, food products, etc.

Another object is to provide an improved refrigerator having automatically controlled steri10 lization.

. A further object is to provide an improved method of subjecting foods, food products, etc., to measured radiation by employing sterilizing radiations of predetermined and repeated dura15 tion.

A feature of the invention relates to a housing for foods, food products, etc., having on its interior a source of sterilizing radiations together with means for enhancing the sterilizing action 20 of said radiations.

Another feature relates to a refrigerator having an interior source of radiations which is rendered automaticaly effective for a predetermined duration each time a door or similar mem25 ber is opened or closed.

A further feature relates to a refrigerator or similar device having its interior surface, or at least a suitable portion thereof,, provided with a specially designed coating for efficiently diffusing 30 and/or reflecting sterilizing radiations such as ultra-violet rays or the like.

A further feature relates to the organization, arrangement and relative location of parts which go to make up a relatively simple and economi35 cal sterilizing refrigerator or similar device.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following descriptions and the appended claims.

While the invention will be disclosed herein as embodied in particular form of apparatus, it will be understood this is done merely for the purpose of explaining the invention. While, therefore, the drawing shows schematically a 45 refrigerator embodying the invention, it will be apparent that the broad inventive concept can be embodied in other types of devices without departing from the spirit and scope of the invention.

Accordingly, in the drawing Fig. 1 is a perspective view of a refrigerator embodying features of .the Invention;

Fig. 2 is a sectional view of the refrigerator of Fig. 1 with the door closed;

Fig. 3 is a diagrammatic curve showing the (CL 62—89) relation between intensity and duration of the sterilizing rays;

Fig. 4 is a schematic diagram of one form of timing arrangement; and

Fig. 5 is a schematic circuit diagram of an al- 5 ternative timing arrangement for controlling the radiation lamps according to the invention.

Referring more particularly to Figs. 1 and 2, the numeral ί indicates any suitable enclosure or housing adapted to contain foods, food-stuffs, or 10 similar materials which tend to change their taste or chemical characteristics by reasons of bacteria or similar organisms. For convenience of description it will be assumed that the device I is a refrigerator of any well known construction. 15 While the drawing shows a refrigerator of the artificial cooling type wherein. the cooling unit 2 is refrigerated by gas, electricity, etc., it will be understood that any other manner of cooling . the interior of device I may be employed, for ex- 20 . ample, by ice, evaporation, or the like. Furthermore, while the drawing shows the refrigerator provided with a single main door or access member 3, it will be understood that any other form of access member, such as a window or the like, 25 may be provided in addition to the main door 3. Suitably mounted within the food compartment or compartments of the refrigerator are a pair of lamps 4, 5, although it will be understood that in this respect the invention is not limited to 30 ' any particular number or disposition of lamps. For example, instead of employing two lamps disposed on opposite side walls of the refrigerator, one large lamp may be employed and suitably mounted within the compartment so as to ra- 35 diate uniformly the entire interior of said compartment. It will also be understood that if the refrigerator is provided with separate food compartments, then one or more lamps may be pro-. vided in each compartment. While, therefore, ₄₀the drawing shows a refrigerator of the single compartment type provided with shelves 6 and I, this is merely for securing simplicity in the drawing. Where a single lamp or pair of lamps is employed as shown in Figs. 1 and 2, it is pref- 45 erable that the shelves be of open-work construction so as to allow the sterilizing radiations from the lamps to pass therethrough and thus enabling the lower and upper portions of the compartment to be radiated. If desired, these shelves 50 may be of glass, quartz or other material which is transparent to the sterilizing radiations. On the other hand, if non-transparent shelves are employed, then an additional lamp or lamps may be mounted between the shelves to insure suffi- 55

3,145,100 dent radiation for the entire contents of the compartment.

While the invention is not limited to any particular character of sterilizing radiations, it is g preferred to employ radiations in the form of ultra-violet rays between 2500 and 2800 A. (Angstrom units) Wave length, as set forth in copending application Serial No. 699,696, filed Nov. 25, 1933. More particularly, the lamps 4, 5 may be 10 designed to generate rays having maximum intensity between 2530 and 2540 A. and with substantially negligible radiation above 2800 A. For a detailed description of such “narrow-band” source of ultra-violet rays, reference may be had ¹⁰ to said application Serial No. 699,696, of which a divisional application Ser. No. 732,430, was filed June 26, 1934.

If desired, the lamps 4 and 5 may be of the in20 direct illumination type, that is, with their bowl ⁸⁰ portions provided with a coating which is capable of efficiently reflecting the ultra-violet rays. Thus the inner surface of the bowl portion of each lamp may be provided with a reflecting coating of aluminum in the manner disclosed in application Serial No. 623,504.

I have found that the paints or enamels ordinarily employed on the interior of refrigerators are not suitable for conserving or efficiently re„ fleeting ultra-violet rays, and this is probably ^3,1 caused by the fact that ordinary paints or enamels as used in refrigerators absorb a very considerable per cent, of the ultra-violet rays which are useful for bactericidal purposes. , I have found _M that if the interior of the refrigerator compart^w ment or compartments is provided with a coating which is capable of reflecting to a considerable extent these bactericidal ultra-violet rays, the sterilizing action is improved and it is possible to employ lamps of smaller wattage. Entirely ⁴⁰ apart from the improved sterilizing action, therefore, the use of lower wattage lamps for the desired sterilizing action, enables less power to be used in maintaining the temperature of the compartment at a desired value. Thus, as indicated in the drawing, the major portion of the interior of the refrigerator compartment as well as the inner face of the door 3, is provided with a coating of aluminum or other similar material capable of efficiently reflecting the bactericidal rays. ⁵⁰ This coating may be applied in any well known manner as by spraying, by the Schoop process, or even by painting and baking. Preferably also, the coating is of diffusely reflecting character so as to reflect the rays as uniformly as possible ⁰⁰ throughout the entire interior of the compartment.

As pointed out above, one of the most serious drawbacks to the utilization of devices such as _M ultra-violet lamps on the Interior ofra- refrigerator is that such lamps generate a considerable amount of heat, thus reducing the running efficiency of the refrigerator. It is highly desirable, therefore, to employ ultra-violet lamps with 66 as low a wattage as possible consistent with the desired bactericidal action. However, the problem is further complicated by the fact that there is a certain minimum intensity and a certain minimum time below which there is very 70 little effective sterilization. I haye found that sterilization by ultra-violet rays of the character set forth herein is normally governed by photochemical lamps; that is, the total amount of sterilization is directly proportional to intensity and also to duration, so that for a given degree of sterilization, one-half as much sterilizing intensity is required if the duration is double, and vice-versa. However, while this relation is tnie for a relatively wide range of intensities, at the low intensities there is a threshold value below ₅which the relation does not hold, as indicated by Fig. 3, wherein the point P represents this threshold intensity. If, therefore, the lamps 4 and 5 are designed to generate only a low intensity in the neighborhood of this threshold value, there will ιθ be considerable chance of the sterilization being ineffective or at least non-uhiform. Instead, therefore, of employing low wattage lamps operating for a proportionately long time, I haVe found that reliable and uniform, sterilization 15 can be achieved without undue heat generation! by employing relatively high intensity lamps which are allowed to operate intermittently for predetermined fixed intervals, preferably every time the door or other access member is opened 20 and closed. Since low intensity lamps require a relatively long time to achieve satisfactory sterilization, it is entirely possible that foods may be inserted and withdrawn from the compartment before the necessary sterilizing action has taken _2Splace. This and other disadvantages are overcome by employing sources which produce intensities of bactericidal rays well above the threshold intensity, and which are allowed to operate for a proportionately shorter duration each time ₃θ the door or other access chamber is closed after the insertion of food material or the like into the compartment.

By employing a narrow-band ultra-violet lamp of the type disclosed in said application Serial No. 35 699,696, the greater part of the electrical energy impressed upon the lamp is transformed into useful bactericidal flux, whereas with ordinary ultraviolet lamps of the “broad-band” type, a great deal of energy is expended in producing ultra- ₄₀violet and other rays which are useless for bactericidal purposes and are even detrimental to the taste of the food, as disclosed in said application Serial No. 699,696. By employing relatively high intensity ultra-violet lamps which are de- ₄₅signed to produce a relatively narrow band of light wavelengths, e. g., 2500 to 2800 A., and by operating these lamps for predetermined fixed and limited durations each time the door or other access member is closed after the insertion of ₆θ food material, and by conserving the bactericidal flux through the intermediary of the aluminum coating.lt is possible to achieve substantially complete and uniform sterilization of the materials within the food compartment, and with a mini- 55 mum of undesired heat energy.

While any well known means may be used for timing and limiting the duration of the radiation each time the refrigerator door is closed, there are shown two alternative arrangements in Figs. 4 60 and 5 of the drawing- Referring to Figs. 1 and 2, it will be seen that there is mounted within the refrigerator a timing control device indicated generally by the numeral 8. Slidably mounted in a wall of the, device 8 is an arm 9 which carries 65 at its inner end a one-way rack which is normally held in its forward position by spring ii. The device is so positioned within the refrigerator that just as the door 3 closes it engages the arm 9 and moves fit against the action of spring II. 70 Rack 10 in sliding, engages the associated ratchet wheel which winds up spring 12. Spring 12 in turn rotates the commutator 13 which is controlled by a timing escapement (not shown). When the refrigerator door is open the disc 13 7s

196 3 approximately 12 millimeters pressure, or a suitable mixture of these gases. The tube 28 is preferably made of material capable of transmitting rays in the band between 2500 A. and 2650 A. For example, this tube may be made of “Corex” 5 tubing and preferably the center section 29 has a very thin wall section, preferably less than onehalf mm. in thickness. The electrodes 30 and 31 are preferably in the form of molybdenum coils which are sealed into and supported at the ends 10 of the tubes in any well-known manner. The partciular lamp shown is designed· to operate at an. impressed voltage of 220 v. A. C. and with a current of 12.5 ^: milliamperes flowing therethrough. ¹⁵

This is a division of application Serial No.

698,265, filed November 16, 1933.

An application Serial No. 243,574, has been filed December 2,1938, as in part a continuation of the present application. 20