US2213035A - Air lock for a sifter - Google Patents

Description

Aug. 27,1940.

E. G. BERRY AIR LOCK FOR A SIF'IER Filed Dec. 20, 1937 llw' VE T" EUGENE G. BERRY Patented Aug. 27, 1940 STTES AIR LOCK FOR A SKFTER nois Application December 20, 1937, Serial No. liiilfi'ilz ll Claim.

This invention relates to an air lock primarily designed for use in connection with sifters but adapted for other uses.

In sifting flour and the like material, it is common practice to use a sifter box having several sieves covered with bolting cloth therein through which the flour passes. boxes are provided with discharge openings through which the sifted material passes.

It has been discovered that air currents enter through the discharge openings and strike or exert pressure against the bottom of the bolting cloth with the result that the sifting of material through said cloth is materially retarded.

It furtherappears that this condition has prevailed ever since such sifters were used without anyone discovering that the sifting efliciency of the bolting cloth was materially reduced through the backing up effect of the air currents.

In the sifting of material used in food products, it is highly essential to keep the same pure and clear of foreign matter such as metal or the like. For this reason it is desirable that an air lock be constructed without the use of springs or such parts as might break or chip and find their way into the sifted material.

It is therefore an object of this invention to provide a simple form of air lock that is free of springs, hinge joints and such parts as might breaker chip off and find their way into the sifter material.

The invention comprises the novel structure and combination of parts hereinafter'described and more particularly pointed out and defined in the appended claim.

In the accompanying drawing which illustrates a preferred form of this invention and in which similar reference numerals refer to similar features in the different views:

Figure 1 is an elevational View of an air lock embodying this invention with a part broken away.

Figure 2.is a top plan view of the structure shown in Figure 1.

In the drawing which illustrates one embodiment that this invention may assume, there is shown a substantially square sheet metal chute member I having a surrounding flange 2 upon its upper edge. The flange 2 is adapted for attachment to the bottom of a sitter box, parts of which are indicated at 3, such as is shown in the Reimuler and Berry application Serial No. 131,821 filed March 19, 1937. For the purpose of illustrating one way in which the flange 2 may be secured to the sifter box, apertures 4 are These sifter shown in the flange 2 for receiving screws or bolts or the like.

The chute member 5 is provided with a bottom ring plate ii which may be soldered thereto. This plate 5 is provided with a circular aperture 6 that corresponds with the diameter of a cylindrical collar l which has a flange soldered to the bottom plate so that the opening in the collar will r gister with said aperture. This collar is provided with a bead 8 at its lower end and forms a support for a stocking leg clamp (not shown).

Against the upper part of the rear wall of the chute l and within such chute there is secured an angle member 8. This angle member is secured by soldering one flange to the rear Wall of the chute with the other flange to extending inwardly as shown in Figure 1.

A valve flap 5 made of spring tempered phosphorus bronze about .005 of an inch thick has its rear edge soldered to the lower side of the flange 8a and additionally secured by rivets Hi. This flap fits freely within the mouth of the chute I so it can readily flex downwardly as shown in dotted lines in Figure 1 when material from the sifter box strikes the same in sufficient volume. The vibration of the sifter box materially aids this downward flexing movement.

It has been discovered that when a thin sheet of phosphorus bronze is spring tempered it acquires a high degree of elasticity that causes it to readily spring to a horizontal position or to right itself after a flexing operation. It has been further discovered that when such a valve flap is attached close to the sifter box that the vibrations arising from the operation of the box will materially aid and induce a downward flexing movement of the valve flap.

Upon the interior front wall of the chute I, there is secured a second angle l l having its outstanding fiange lla overlap the forward margin or edge of the flap 9.

Along the interior sides of the chute l are soldered small angle members l2, the outstanding flanges of which overlap the top side edges or margins of the flap 9. Thus there is an overlapping lip or narrow flange upon the front and side margins of the flap valve ii that limits its upward movement when the same springs back from its dotted line position shown in Figure 1.

The valve flap 9 is extremely flexible or resilient and does not require much force to flex the same downwardly as shown in dotted lines in Figure 1 for the passage of sifted material between its front edge 9a and the adjacent wall of the chute especially when it is vibrated. The

sifted material in passing through this space will be more or less concentrated or compacted and will prevent incoming currents of air.

It might be mentioned that the sifted material that may drop upon the corners of the bottom plate 5 will be soon shaken off through the vibrations of the sifter.

Thus the valve fiap 9 will permit the discharge of material but will prevent incoming currents of air that have heretofore retarded the sifting of material through the bolting cloth.

Due to the fact that this valve flap is not hinged nor controlled by springs there is no part that can break and produce particles that will find their way into the sifted material.

It will be appreciated that in using a substantially square or rectangular chute member, it is possible to secure the valve flap along one entire margin so that it can be firmly supported, a fea-. ture that would not be possible if a cylindrical chute member were used. It will further be appreciated that the use of a thin phosphorus bronze valve fiap that is spring tempered and subjected to the vibrations arising from a sitter box will readily accomplish the purpose desired.

From the foregoing, it will be apparent that a very simple and novel flap valve has been invented that is especially adapted as an air lock for sifters to prevent air currents from entering and retarding the passage of material through the bolting cloth.

I am aware that many changes may be made and numerous details of construction may be varied through a Wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention:

The combination with a vibratory sifter having a movable frame defining an outlet opening for material, an air lock comprising a chute having a rectangular upper portion, an outwardly extending peripheral flange at the top of the chute for attaching it in suspended position to the frame around the outlet opening, a thin, flexible, rectangular metallic flap extending into the chute, and members respectively disposed at opposite top edges of the chute forming inwardly directed flanges lying substantially in a plane perpendicular to the chute axis, said flap being rigidly secured at one end to one of said flanges and having its free end extending under the other of said flanges, the latter flange acting to restrain the flap against upward flexing movement, but enabling downward flexing movement thereof under weight of material from the outlet opening.

EUGENE G. BERRY.

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