Laterally reinforced produce roller

The present invention comprises a novel roller for use on agricultural produce grading, sorting, cleaning and conveying equipment. The roller comprises a cylindrical hub having protruding fingers thereon which extend outward from the hub in a direction perpendicular to the hub axis and inclined away from the direction of rotation of the hub. The roller further comprises lateral support shoulders which allow the fingers to flex properly in the direction of rotation while providing increased rigidity in a lateral direction to improve grading opening uniformity and consistency. A concave shape on the outer surface of these lateral support shoulders also defines an improved grading opening shape which serves to increase grading uniformity as well. A smooth surface to the grading opening surfaces also prevent accumulation of mud and dirt in the critical grading opening area.

THE FIELD OF THE INVENTION
 This invention relates generally to the field of agricultural processing
 equipment and more specifically to equipment for grading, sorting,
 conveying and cleaning oblong and round produce. More particularly, the
 present invention is a roller for use on produce grading equipment with
 conveyors comprised of substantially parallel, driven roller shafts and is
 most suitable for use in processing potatoes and similar produce.
 BACKGROUND
 When produce such as potatoes, onions and other crops are harvested, the
 produce varies greatly in size, shape and weight. Different markets and
 customers often have disparate needs for produce of a given dimension or
 attribute. Frequently, produce of a given size or shape is in higher
 demand and will command a higher price. Consequently, harvested produce
 must be segregated according to size, shape or some other attribute to
 meet the needs of the customer and the market. Once sorted or graded, the
 produce of a specific size or characteristic may be shipped to the
 customer or market demanding that size or characteristic.
 Potatoes, onions and other subterranean produce often have large amounts of
 soil and small rocks adhered to the produce when harvested. This material
 must be removed before the produce is weighed for sale. Soil removal can
 become difficult when the soil is relatively moist because the mud will
 adhere to equipment sometimes causing it to clog and sometimes causing it
 to become lubricated with a film of mud.
 Potato harvesters often use a grading apparatus which comprises a
 succession of closely spaced roller shafts containing rollers with
 protrusions thereon which act to propel the potatoes along a grading path.
 The first roller shafts encountered by the potatoes are typically closely
 spaced with radial protrusions which serve to turn and propel the potatoes
 thereby loosening soil, rocks and mud which may have adhered to the
 potatoes. Subsequent sets of roller shafts are spaced increasingly further
 apart to allow the smaller and then larger grades of potatoes to pass
 between the rollers and fall into grading containers or conveyors for each
 grade of potato.
 Problems may arise with this type of grader or sorter when excess mud is
 allowed to build up on the surfaces of the rollers. One problem occurs
 when mud builds up on the roller surfaces which define the opening through
 which the potatoes are graded. Mud buildup causes an effective decrease in
 the opening size and therefore a decrease in the potato size passing
 through the grader opening. Another problem occurs when roller surfaces
 become lubricated and clogged with mud such that potatoes are not properly
 propelled along the grader path. This causes potatoes to build up on the
 grader without forward movement. If this condition persists, potatoes
 accumulate and spill over the sides of the grader path putting a halt to
 grading operations.
 Another problem occurs when grading rollers do not have proper elastic
 deflection during operation. Rollers and protrusions therefrom must
 deflect in a direction parallel with the grading path so as to prevent
 excessive impact forces on the produce. However, the protrusion must be
 sufficiently rigid to propel the produce along the grading path. Roller
 protrusions must also have sufficient lateral rigidity to retain a uniform
 shape through grading openings as produce is propelled across the
 openings. Proper protrusion rigidity contributes to uniform grading and
 efficient produce propulsion.
 In reference to FIG. 1, a prior art roller may be used to illustrate the
 problems of the prior art. Prior art rollers, such as the "acorn" roller
 of FIG. 1, have tightly spaced ribs 2 and nubs 4 which create narrow
 crevices 6 where mud and dirt can easily accumulate. The concentration and
 density of the ribs 2 and nubs 4 also produces non-aggressive propulsion
 characteristics with no defined protrusions to grasp and propel the
 produce along the grading path. This lack of propulsion results in
 diminished production rates, especially in muddy conditions when the
 rollers are lubricated with mud.
 The easy accumulation of mud and dirt in the many crevices 6 on the "acorn"
 roller also results in inaccurate sizing. In reference to FIG. 2 where a
 prior art "acorn" roller shaft layout is shown, it can be seen that these
 prior art roller are configured in such that the centerline 10 of each
 roller on a first shaft 14 aligns with the centerline 12 of each roller on
 the next successive shaft 16 thereby creating a somewhat distorted
 hexagonal pocket 20 or opening between rollers 14 and shafts 16 and 18.
 Produce of a particular size or grade will fall within this opening 20
 unless dirt and mud build up on the surface of rollers 14 thereby
 decreasing the size of opening 20 and consequently the size of the produce
 falling through the opening 20. It can also be seen that produce slightly
 larger than opening 20 will rest over opening 20 without being propelled
 down the grading path if an aggressive protrusion pattern is not
 available. This is often the case when tightly spaced ribs 2 and nubs 4
 clog with dirt and mud.
 SUMMARY AND OBJECTS OF THE INVENTION
 The present invention comprises a novel roller for a produce grader roller
 shaft which provides improved produce propulsion and grading uniformity
 under muddy and dirty conditions.
 Some embodiments of the present invention comprise an elastomeric roller
 preferably constructed of rubber or similar material. These embodiments of
 the present invention comprise a central cylindrical roller hub from which
 elongated fingers protrude in a direction perpendicular to the cylindrical
 axis of the hub. These fingers may be inclined away from the direction of
 rotation of the roller such that the base of the fingers leads the tips of
 the fingers during rotation. Additionally, the sides of these fingers are
 reinforced by lateral support shoulders which extend from the sides of the
 fingers outer surface of the roller hub thereby providing lateral support
 for the roller fingers. These lateral support shoulders are segregated by
 grooves which separate the shoulders of each distinct finger. This
 shoulder separation provides lateral support to the finger against
 excessive flexure in the lateral direction while allowing the finger to
 flex along its path of rotation so as to prevent excessive impact and
 bruising of the produce.
 The outer surface of these shoulders also serves to define the shape and
 size of the grading openings between roller shafts. As potatoes are
 generally oval in shape, a substantially oval opening shape will provide
 the most uniform grading. This oval opening shape is achieved by giving
 the shoulders a concave outer surface shape. In this manner, two adjacent
 rollers will form a half-oval shape as one side of the grading opening
 thereby approximating an oval produce shape.
 Accordingly, it is an object of some embodiments of the present invention
 to provide a produce grader with more uniform and reliable grading
 capacity.
 It is another object of some embodiments of the present invention to
 provide a produce grader with increased propulsion capacity.
 It is a further object of some embodiments of the present invention to
 provide a produce grader with improved capacity and accuracy under muddy
 and dirty conditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 The present invention may be embodied in other specific forms without
 departing from its spirit or essential characteristics. The described
 embodiments are to be considered in all respects only as illustrative, and
 not restrictive. The scope of the invention is, therefore, indicated by
 the appended claims, rather than by the foregoing description. All changes
 which come within the meaning and range of equivalency of the claims are
 to be embraced within their scope.
 The figures listed above are expressly incorporated as part of this
 detailed description.
 In reference to FIGS. 3-5, the novel features of some preferred embodiments
 of the present invention may be illustrated. Some embodiments of the
 present invention comprise a produce grading roller 28 having a
 substantially circular cylindrical roller hub 30 with a circular
 cylindrical outer surface 32. Flat hub ends 34 provide an abutting surface
 for arranging a series of adjacent rollers on a shaft. Propulsion fingers
 36 propel produce along a grading path 38 with progressively higher roller
 spacing 40 which corresponds to progressively larger grades of produce.
 Eventually, the produce will fall through an opening 42 corresponding to a
 particular grade of produce or be ejected from the end of the grading path
 as oversize material.
 Propulsion fingers 36 comprise elongate protrusions which preferably have
 rectangular or, more preferably, square cross-sections. A preferred
 embodiment of fingers 36 has a square cross-section with sides of about
 3/4" in length and works well in a potato grading process. However, other
 cross-sectional shapes and sizes will also work well with potatoes and
 other similar produce.
 A preferred embodiment of fingers 36 also comprises a rounded tip 44 formed
 by the convergence of a leading surface 46 and a trailing surface 48.
 Fingers 36 protrude in a radial direction a protrusion distane 50 of
 approximately 11/4" to approximately 13/4" from the outer surface 32 of
 hub 30 to tip 44 with 11/2" being a preferred distance for potato grading
 applications.
 In preferred embodiments, fingers 36 will also be inclined away from a
 direction of rotation such that an extension of the leading surfaces 46 of
 fingers 36 will be substantially tangent to the outer cylindrical surface
 32 of hub 30. This tangential relationship between leading surfaces 46 and
 may vary by about 15 degrees in either direction, however, a relationship
 very near to tangent is most preferable for potato grading applications.
 In order to drive roller 28, a shaft 62 is placed through a series of
 adjacent rollers and connected to a rotating apparatus. Therefore, roller
 28 comprises an axial drive aperture 64 extending completely through hub
 30 for receiving a drive shaft 62.
 A preferred embodiment of the present invention further comprises lateral
 support shoulders 66 which brace fingers 36 against lateral deflection.
 Shoulders 66 brace fingers 36 against lateral movement, but do not
 directly brace against movement in the direction of rotation. This allows
 fingers 36 to flex in the direction of rotation thereby giving fingers 36
 a lighter touch on the produce being graded. However, shoulders 66 prevent
 lateral deflection thereby providing greater uniformity of grading as the
 grading opening 42 is not distorted by deflection of fingers 36 as produce
 contacts fingers 36. Shoulders 66 are segregated by grooves or saddles 68
 which preferably extend inward to the outer cylindrical surface 32 of hub
 30.
 Shoulders 66 preferably have a concave outer surface 70, as shown in FIG.
 5, which gives shoulders proper lateral rigidity and defines an improved
 grading opening shape 42. Concave outer surfaces 70 form a substantially
 half oval shape 72 for opening 42 which better approximates the shape of a
 potato or other round or oblong produce. This shape 72 provides more
 uniform grading as produce fits snugly into the opening without twisting
 or wedging into opening corners as in prior art openings.
 A further advantage rendered by shoulders 66 is the ability to use higher
 compressive forces between rollers 28 on a shaft without distorting the
 shape of the rollers 28. Shoulders 66 reinforce the hub 30 of the roller
 28 against compression so that rollers 28 can be compressed together on a
 shaft more tightly thereby reducing the possibility of foreign matter
 becoming entangled between rollers 28.
 Lateral reinforcement provided by shoulders 66 also allows the use of a
 softer rubber or similar elastomeric material as lateral rigidity
 comparable to harder rubbers can be achieved with a softer rubber
 reinforced with shoulders 66. Softer rubber rollers damage produce less
 and render the equipment more versatile by allowing use with more tender
 produce.
 When produce which is slightly larger than opening 42 falls onto openings
 it is summarily ejected by fingers 36 on rollers found on the next
 successive roller shaft. Fingers on these rollers will positively engage
 oversize produce and propel it to the next grading opening 42 which will
 eventually be a larger grade or size.
 It should be noted that the preferred roller embodiments of the present
 invention are preferably configured in an offset roller configuration
 wherein rollers on a first roller shaft 62 have a centerline 74 which
 aligns with a dividing line 76 between rollers 28 on a next subsequent
 roller shaft 78. In this offset configuration, fingers 36 on rollers 28
 define a portion of grading opening 42 and serve as positive ejectors of
 oversize produce. This configuration, using the novel rollers 28 of the
 present invention, increases grading capacity, throughput, speed and
 accuracy as well as reliability in adverse conditions of mud and dirt.
 Another advantage of the present invention derives from the smoothness of
 the surfaces which define the grading opening 42. These surfaces may
 include the exposed surfaces of shoulders 66, outer hub surface 32,
 grooves or saddles 68, and the sides of fingers 36 as well as other
 surfaces which may help define the grading opening in embodiments of the
 present invention. These grading opening surfaces are preferably smooth
 with rounded edges and radius transitions between surfaces. This
 smoothness serves to inhibit accumulation of dirt, mud and other
 deleterious materials and preserve the uniformity of the grading opening
 size and dimensions.
 The present invention may be embodied in other specific forms without
 departing from its spirit or essential characteristics. The described
 embodiments are to be considered in all respects only as illustrative, and
 not restrictive. The scope of the invention is, therefore, indicated by
 the appended claims, rather than by the foregoing description. All changes
 which come within the meaning and range of equivalency of the claims are
 to be embraced within their scope.