US3587857A - Device for sorting fruit - Google Patents

Abstract

APPARATUS AND PROCESS ARE DISCLOSED FOR SORTING FRIUT-TYPICALLY DATES-ACCORDING TO THE MOISTURE CONTENT OF THE INDIVIDUAL UNITS IN THE BATCH. THE DATES ARE ACCELERATED BY SLIDING DOWN A CHUTE, AND THEN PROJECTED AGAINST A SURFACE WHEREBY THEY REBOUND TO A DEGREE RESPONSIVE TO THEIR SOFTNESS WHICH, IN TURN, IS RELATED TO THEIR MOISTURE CONTENT.

Description

United States Patent David Reznik Berkeley, Calif.

Nov. 14, 1968 June 28, 1971 The United States of America as represented by the Secretary of Agriculture lnventor Appl. No. Filed Patented Assignee DEVICE FOR SORTING FRUIT 5 Claims, 6 Drawing Figs.

US. Cl 209/1l9 Int. Cl. B07b 13/10 Field ofSearch 209/112, 114, [16,119,120

[56] References Cited UNITED STATES PATENTS 2,316,556 4/1943 Butcher 209/1 19X 2,802,471 8/1957 l-leitmann...v 209/1 19X 3,4! 1,626 I H1968 Kreamer 209/119 Primary Examiner-Richard A. Schacher AnomeysR. Hoffman and W. Takacs ABSTRACT: Apparatus and process are disclosed for sorting fruittypically dates-according to the moisture content of the individual units in the batch. The dates are accelerated by sliding down a chute, and then projected against a surface whereby they rebound to a degree responsive to their softness which, in turn, is related to their moisture content.

Dry Dates Moist Dates *4 a Dry Dates Moisi Dates F/G. i

F/G. 3 DAVID REZNIK 1%VENT2R BY Ma ATTORNEYS PATENTEU JUNZB 1971 3581857 SHEET 2 [1F 3 DAVID REZNIK INVENT R flmL-k BY M Mau- ATTORNEYS PATENTEU JUH28 um SHEET 3 [1F 3 DAVID REZNIK INVENTOR BY%% W7ZM ATTORNEYS DEVICE FOR SORTING FRUIT A nonexclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to and has among its objects the provision of novel apparatus and process for sorting dates or other fruit. Further objects of the invention will be evident from the following description taken in conjunction with the appended drawing.

In the drawing, wherein like numeral represent like parts:

FIG. 1 is a three-dimensional view of one embodiment of the sorter of the invention.

FIG. 2 is a cross section of chute 1 on an enlarged scale.

FIG. 3 is a sectional view of chute 1 on an enlarged scale showing the position assumed by dates sliding therein.

FIG. 4 is a front elevation of the sorter of FIG. 1 which is provided with a modified form of impingement plate.

FIG. 5 is a plan view of another embodiment of the sorter of the invention.

FIG. 6 is a plan view of still another embodiment of the sorter of the invention.

The problems with which the invention is concerned and the application of the invention are explained below, having particular reference to dates. It is to be understood, however, that a similar situation is encountered with other produce and in its broad compass the invention is applicable to fruits in general, typically figs, raisins, dried prunes, dried apricots, and the like.

It is common practice, particularly in California and Arizona, to harvest dates by collecting all the mature dates from the trees at a single picking. The product, therefore, contains fruit of varying moisture content ranging from very hard (dry) ones to those which are soft and moist. The crop is not saleable in this condition; it must be sorted to segregate the dry, moist, and intermediate fruits. This sorting is commonly performed manually. In the packing sheds the harvested-crop is carried on conveyor belts past a group of skilled inspectors who pick out the dates according to moisture content and place them in appropriate containers. Although the industry has long recognized the expense of this manual sorting operation and its dependence on the human factor, there has not been available heretofore any system for performing the sorting effectively and yet at lower cost.

It is a particular object of the invention to provide the means whereby to surmount the problems outlined above. A special advantage of the invention is that it provides a system whereby the sorting is done not only mechanically but also with a high degree of efficiency.

The sorting system in accordance with the invention utilizes certain properties of the fruit which vary with softness, hence with moisture content. One property is that of resilience. The hard (low-moisture) fruit is more resilient than soft (highmoisture) fruit so that when individual fruit units are dropped on a surface, the low-moisture ones will bounce farther than the high-moisture ones. Another property utilized in accordance with the invention is that the low-moisture fruit exhibits a lesser degree of friction when rubbed against a surface than does the high-moisture fruit.

The manner in which these principles are applied is now explained in connection with FIG. 1 in the annexed 'drawings:

Reference numeral 1 designates a feed chute which includes an upper leg 2 and a lower leg 3. In operation, the dates to be sorted are introduced into the top of leg 2 whereby they slide down the chute with accelerating velocity and impinge on plate 4.

For best results it is preferred that the dates be introduced into chute 1 in spaced relationship, for example, with a distance of about 1 Lto 3 inches between individual units. This type of feeding may be effectuated, for example, by spacing the dates 5 on a conveyor belt 6 which drops the individual fruit units serially into chute 1. Such spaced feeding prevents the movement of one date from interfering with that of another. For example, if a moist date is introduced first and followed immediately by a dry date, the slower acceleration of the leading date (due to its relatively high friction characteristic) will tend to impede the acceleration of the following date. Where, however, the dates are spaced there is no interference, and each will assume a speed attributable to its own characteristics.

Excellent results have been attained with apparatus wherein chute 1 has a length of about 5-6 feet and the upper portion (leg 2) is disposed at an angle of about 40-50 from the horizontal. Lower leg 3 subtends a smaller angle (about 5 to 10) with the horizontal to ensure that the dates present a side (as opposed to an end) when they impinge on plate 4.

Chute 1, particularly upper leg 2 thereof, functions in two ways: It serves to give the entering dates a desirable downward velocity so that in a subsequent step they can be bounced off plate 4. Secondly, a certain degree of sorting occurs as the dates slide down the chute because the low-moisture dates will assume a higher velocity (due to their lower friction properties) than will the high-moisture dates. This difference in velocity assists the subsequent separation based on resiliency. Because the low-moisture dates are moving faster, they will bounce further than they would if they were moving at the same speed as the high-moisture dates.

As shown in FIG. 2, chute l is rounded in cross section, comprising a half-circle or preferably somewhat more, e.g., about 200 of are. This rounded or arcuate conformation has the benefit that no matter how the dates are oriented when introduced into the top of the chute, they will assume a lengthwise position as shown at 5 in FIG. 3. This is desirable so that when the dates leave the end of the chute and strike impingement plate 4, they will not tend to roll but rather bounce. It is obvious that if the dates were crosswise in the chute they would tend to roll (when they struck plate 4) and this would not be conducive to the desired sorting effect.

Positioned beneath chute l is a bin 7 open at the front and top, having a sloping bottom 8, and subdivided by partitions 9, 10, 11 into compartments 12, 13, 14, and 15. These compartments serve to receive and discharge sorted dates as hereinbelow explained.

Plate 4 is mounted above and at the rear of bin 7 in a position so that the dates leaving chute 1' will impinge on this plate. Adjustable brackets 16 serve to support plate 4, and to provide the means whereby the attitude of this plate can be varied. In order to direct the impinging dates forwardly into the appropriate compartments of bin 7, the short (crosswise) axis of plate 4 is slanted downwardly-usually at an angle of about 10l5 from the horizontal. This crosswise tilting of plate 4 is also desirable to obtain a scavenging effect. Individual dates which come to rest after striking plate 4 will not remain thereon, but roll off the plate into an appropriate compartment.

In the preferred form of the apparatus, the long (lengthwise) axis of plate 4 is slanted downwardly toward the right-hand end of bin 7, at an angle of about l0-l5 from the horizontal. The slanting in this dimension provides a better differentiation in the degree of rebound exhibited by dates of different moisture content. The device of FIG. 1 illustrates this preferred arrangement wherein plate 4 is tilted downwardly not only toward the front of bin 7 but also toward the righthand end of the bin.

In operation, dates slide down chute 1, impinge on plate 4, bounce off this plate, and fall in one or the other of compartments 12, 13, 14, or 15 depending on their moisture content. For example, dry dates because of their high degree of resilience and their high speed of approach (due to low friction characteristics), will bounce a maximum distance and fall in compartment 12. Conversely, moist dates because of their lower degree of resilience and their slower speed of approach (due to their high friction characteristic) will bounce only a small distance and fall into compartment 15. Dates of intermediate moisture content will bounce into compartments 13 and 14 depending on their relative moisture contents. The sorted dates then roll or slide out the front of bin 7, and the fruit from each compartment may be received in suitable containers placed beneath the respective compartments.

It will be obvious to those skilled in the art that various modifications may be made within the spirit of the invention. For example, the number of compartments in bin 7 may be varied as desired. One may provide only two compartments for splitting the raw material into two batches-one of dry dates and one of moist dates. Another plan is to provide three compartments to split the raw material into three batchesdry, intermediate, and moist. Alternatively, one may provide more compartments than the four shown. It is also obvious that the positions of the partitions defining the compartments may require some adjustment depending on the kind of fruit and the composition thereof, particularly the homogeneity (or heterogeneity) of the individual units to be sorted. The positions of the individual partitions may be adjusted to provide optimum results by applying pilot tests. This may be done, for example, in the following manner: A representative sample of dates (a pound or two) is removed from the batch to be sorted. This sample is sorted by inspection and segregated into four lots A, B, C, D (arranged from very dry to very moist). Individual dates from each lot are dropped into the chute and observation is made of which compartment they are landing in. The partitions are then moved to left or right and adjustments made of the tilt of plate 4 (or plate 20) so that essentially all the A dates fall in compartment 12, the B dates in compartment 13, the C in 14, and the D in 15. When this has been done, the apparatus is ready for sorting the main batch of dates.

Variation is also possible with the type of surface presented by impingement plate 4. This element may be, for example, a metal sheet with a smooth top surface. Generally, however, it is preferred that the top surface be somewhat roughened, as by coarse sanding, knurling, or the like. The effect of roughness can also be attained by using a sheet of perforated metal or stiff screening as the plate.

In the embodiment of FIG. 1, plate 4 presents a planar surface. Altematively, however, one may employ a curved surface as shown in FIG. 4. Referring thereto, plate 20 corresponds to plate 4 in the modification of FIG. I, and the other parts are as in said FIG. Plate 20 instead of being planar is warped. Its short axis is tilted downwardly to direct rebounding dates toward the front of bin 7, and to secure a scavenging effect. The plate is also warped or twisted so that its right-hand front end dips downwardly, this drip providing a better spread in the degree of rebound exhibited by dates of different moisture content.

Reference is now made to FIG. which depicts an embodiment wherein a moving surface is used for the impingement. In this form of the invention, an endless belt 30 of sheet metal is mounted horizontally on rollers 31 (one of which is shown in the FIG.). Roller 31 is driven by any suitable means (not illustrated) to traverse belt 30 in the indicated direction. In a typical installation, belt 30 is about inches wide, and is traversed at about 80 ft. per minute. Chute l is provided as in the above-described embodiments. Also provided are a series of receiving compartments 32, 33, 34, and 35. Collecting blades 36, 37, 38 are mounted above belt to direct dates lying on the belt surface into the appropriate compartment.

In operation, dates slide down chute 1 and impinge on belt 30. The dry (hard) dates because of their high resiliency and high speed of approach are little affected by the movement of belt 30 and rebound into compartment 32. The softer dates are more affected by the movement of belt 30 and hence their trajectory is deflected in the direction of movement of the belt. The result is that these dates will come to rest on the belt in a position dependent on their relative softness. For example, the softest dates will come to rest adjacent to the righthand side of the belt whereby they will be directed into compartment by blade 38. Somewhat harder dates will alight nearer the center of the belt and be directed into compartment 34 by blade 37, and so on.

As in the case of the previously described embodiments, the number of compartments and associated collecting blades may be varied depending on how many fractions the raw material is to be split into. Also, such factors as the positions and lengths of the collecting blades and the speed of belt 30 may be adjusted in accordance with pilot trials to achieve an optimum sorting effect.

In order to increase the capacity of the device of FIG. 5, one may extend belt 30 and provide several sorting unitseach including a chute and associated compartments and collector blades-along the length of the belt.

FIG. 6 depicts an alternative embodiment wherein rotating disc 40 is as the impingement surface in place of belt 30 of FIG. 5. With this modification, receiving compartments 4], 42, and 43 and associated collecting blades 44 and 45 are positioned about the periphery of disc 40 to receive the dates whose trajectories are affected to a greater or lesser degree by the rotation of disc 40.

In the embodiments hereinabove described the sorted dates are received in bins or compartments. It will be obvious to those skilled in the art that other kinds of receiving devices may be employed. Thus, for example, the different fractions may be received on conveyor belts, or other mechanical arrangements for carrying the fruit to a desired location.

I claim:

1. A process for sorting fruit according to the moisture content of individual units which comprises.

a. sliding fruit units along a downwardly inclined surface to impart an acceleration to the units which is higher for the drier units than for the moister units;

b. impinging the accelerated units against a surface; and

c. separately collecting the units which rebound from the surface at different velocities.

2. Apparatus for sorting fruit according to the moisture content of individual units which comprises, in combination:

a. an inclined chute for feeding fruit units and imparting acceleration thereto;

b. an impingement surface mounted beneath the chute for impingement of the accelerated units thereon;

c. a series of compartments for separately receiving the individual units which rebound from the impingement surface at different velocities;

d. one of said compartments being positioned to receive the units which display minimum tendency to rebound upon impingement;

e. one of said compartments being positioned to receive the units which display maximum tendency to rebound on impingement; and

f. wherein the length and inclination of the chute are such that drier fruit units are accelerated to a greater extent than the moister fruit units.

3. Apparatus for sorting fruit according to the moisture content of individual units which comprises, in combination:

a. an inclined chute for feeding fruit units and imparting acceleration thereto;

b. an impingement surface mounted beneath the chute for impingement of the accelerated units thereon;

c. a series of compartments for separately receiving the individual units which rebound from the plate at different velocities;

d. one of said compartments being positioned to receive the units which display minimum tendency to rebound upon impingement;

e. one of said compartments being positioned to receive the units which display maximum tendency to rebound on impingement; and

f. wherein the said impingement surface is provided by a traversing conveyor belt which is traversed in a direction essentially at right angles to the inclined chute.

4. Apparatus for sorting fruit according to the moisture content of individual units which comprises, in combination:

a. an inclined chute for feeding fruit units and imparting acceleration thereto;

b. an impingement surface mounted beneath the chute for impingement of the accelerated units thereon;

tent of individual units, which comprises:

a. imparting acceleration to the fruit units;

b. impinging the accelerated fruit units against a surface while concomitantly moving the surface laterally to the line of movement of the impinging fruit units, whereby the rebound trajectories of the moister fruit units are sidewardly deflected to a greater extent than those of the drier fruit units; and

c. separately receiving the fruit units which rebound from the surface with different rebound trajectories.

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