FIELD OF THE INVENTION

This invention relates to apparatus that is used to break or crack the shells of stone fruit nuts.

BACKGROUND TO THE INVENTION

Pecan trees (Carya illinoinensis) produce fruits that include a single stone or pit, surrounded by a husk. The husk is produced from the exocarp tissue of the flower, while the part known as the nut develops from the endocarp and contains the seed.

These nuts are harvested in the fall and dried to a kernel moisture content of less than about 5%. The drying process is applied to stabilize the nut for storage purposes prior to processing. The species lllinoisnensis include several pecan cultivars. The different cultivars have characteristics that vary with regards to the nut’s shape, size, thickness of the shell, and kernel content, among others. All the cultivars typically have nuts with an ovoid-sphere shape. A sphere represents a very strong shape in nature, however, once a spherical shape has been compromised, even minimally, the structure’s integrity is severely diminished.

Various methods and apparatus have been used to crack and remove shells of stone fruit nuts such as those of pecan trees. These involve the use of side-impact crackers which seek to crack the shell of the nut within the kernel extraction process. Once the nuts are cracked, they are put through a shelling machine (a so-called ‘sheller’), the principal aim of which is to remove the cracked shell. Examples of these include the commercially available ‘Meyer’ and ‘Savage’ shellers.

It is not the function of the cracker to strip the shell off the kernel. Instead, as the name indicates the primary function of the cracker is to create a crack in the shell of the nut. The shelter, which is conventionally used after the cracker, is used to strip the cracked shell with ease and without damaging the valuable kernel.

Conventional shelters are typically highly efficient at performing their function when they are set for relatively low volumes of throughput. However, this efficiency is typically not achievable at higher processing rates. With processing rates that are required for modern production throughputs, the efficiency of the system reduces, and it is common for cracker and shellers in such configurations to achieve an overall recovery in the region of 65% to 75% of intact kernel halves.

The problems mentioned above in respect of pecan tree nuts are also relevant for other types of stone fruit nuts.

OBJECTIVE OF THE INVENTION

It is an objective of the invention to provide a stone fruit nut pre-sheller which at least partly overcomes the abovementioned problem.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a stone fruit nut pre-sheller comprising a frame having first and second ends with a roller rotatably mounted between the first and second ends and provided with drive means at a free end thereof, and a cover which extends at least partially between the first and second ends of the frame; with the pre-sheller including a passage which extends at least partially from the first to the second end of the frame between the roller and the cover, with the cover being shaped and configured relative to the roller to define the passage between it and the roller, and with the passage having - an inlet at the first end of the frame and an outlet at the second end of the frame, and a predetermined cross-sectional area perpendicular to a longitudinal axis of the roller, with the area being sized to allow a stone fruit nut within a predetermined size range to enter the inlet only with its longitudinal axis substantially perpendicular to the cross-sectional area of the passage at its inlet; operatively for a stone fruit nut that is fed into the inlet to be rolled around its longitudinal axis between the roller and the cover to crack the stone fruit nut shell, and for the cracked nut to exit the pre-sheller from the outlet.

There is further provided for the passage to extend linearly and substantially co-axially with the roller, alternatively helically around the roller. There is further provided for the passage to have a progressively decreasing cross-sectional area, with the decrease in cross sectional area being provided by one or both of a progressive increase in the roller diameter between the first and second ends of the frame, and a progressively decreasing distance between the cover and the roller axis between the first and second ends of the frame.

In accordance with a second aspect of this invention there is provided a stone fruit nut pre- sheller comprising a frame having first and second ends with a set of two rollers rotatably mounted between the first and second ends of the frame with longitudinal axes that are substantially co-axially aligned, and with at least one of the rollers provided with drive means at a free end thereof, and a cover which extends at least partially between the first and second ends of the frame; with the pre-sheller including a passage which extends at least partially from the first to the second end of the frame between a nip of the set of rollers and the cover, with the cover being shaped and configured relative to the nip of the set of rollers to define the passage between it and the nip of the rollers, and with the passage having - an inlet at the first end of the frame and an outlet at the second end of the frame, and a predeterminable cross-sectional area perpendicular to the longitudinal axes of the rollers, with the area being sized to allow a stone fruit nut within a predetermined size range to enter the inlet only with its longitudinal axis substantially perpendicular to the cross-sectional area of the passage at its inlet; operatively for a stone fruit nut that is fed into the inlet to be rolled around its longitudinal axis between the set of rollers and the cover to crack the stone fruit nut shell, and for the cracked nut to exit the pre-sheller from the outlet.

There is also provided for both rollers to be provided with drive means at free ends thereof, alternatively for one roller to be driven and for the other to be rotatably connected to the driven roller, further alternatively for one roller to be driven and for the other roller to be freely rotatable.

In accordance with a third aspect of this invention there is provided a stone fruit nut pre-sheller comprising a frame having first and second ends with a set of at least three rollers rotatably mounted between the first and second ends of the frame with longitudinal axes that are substantially co-axially aligned and positioned in a triangle for the rollers to provide a passage extending from the first to the second end of the frame between adjoining surfaces of the rollers, and with at least one of the rollers provided with drive means at a free end thereof; with the passage having - an inlet at the first end of the frame and an outlet at the second end of the frame, a predeterminable cross-sectional area perpendicular to the longitudinal axes of the rollers, with the area being sized to allow a stone fruit nut within a predetermined size range to enter the inlet only with its longitudinal axis substantially perpendicular to the cross-sectional area of the passage at its inlet; operatively for a stone fruit nut that is fed into the inlet to be rolled around its longitudinal axis between the rollers to crack the stone fruit nut shell, and for the cracked nut to exit the pre- sheller from the outlet.

There is also provided for the pre-sheller of the third aspect of the invention to include a cover which extends at least partially between the first and second ends of the frame.

There is further provided for the passage of the pre-sheller of the second and third aspect of the invention to extend linearly and substantially co-axially with the set of rollers.

There is also provided for two or all of the rollers to be provided with drive means at a free end of each thereof, alternatively for one roller to be driven and for the other two rollers to be rotatably connected to the driven roller, further alternatively for one roller to be driven and for the other rollers to be freely rotatable.

There is further provided for the pre-sheller to include two rows of rollers arranged adjacent each other with each roller in the second row of rollers to be arranged centrally to a nip between two rollers in the first row, for each set of three rollers to provide a passage extending from the first to the second end of the frame, and for the frame to support a feeding hopper above the rollers, with the hopper including a feeding tube extending to each of the inlets to the passages.

There is still further provided for the first row of rollers to include ten rollers and for the second row of rollers to include nine rollers, and for the nineteen rollers of the two rows of rollers to provide seventeen passages.

There is still further provided for a plurality of banks of rollers to be installed adjacent each other, with each bank operating independently of the other with its own feeding hopper and drive means. There is further provided for the passage to have a progressively decreasing cross-sectional area perpendicular to the rollers’ axes, with the decrease in cross sectional area being provided by a progressive increase in the roller diameter of at least one, and preferably all, of the rollers between the first and second ends of the frame.

There is still further provided for at least one, and preferably all, of the rollers to be profiled with a helix pattern in its surface.

There is further provided for each roller to include a gear on its free end, with the gears of on all the rollers being the same size to enable the drive means to rotate the rollers at the same rotational speed.

These and other features of the invention are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a top perspective view of a first embodiment of a nut pre-sheller according to the invention;

Figure 2 is an end-view of the pre-sheller of Figure 1 ; and

Figure 3 is top perspective view of a second embodiment of the invention, in the form of a bank of the nut pre-shellers shown in Figure 1 ; and

Figure 4 is a part sectional side elevation of the bank of nut pre-shellers shown in Figure 3.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the pre-sheller (1) of this invention is sized and configured for the processing of pecan nuts. It will be appreciated that its sizing and configuration may be adapted, without departing from the essence of the invention, to be used for the processing of other types of stone fruit nuts. To crack the shell of a pecan nut, a force of about 15 MPa is typically required. Once the shell of the nut is cracked, which means a complete breach in the ovoid-spherical shell has been achieved, the shell breaks apart relatively very easily, requiring far less force than what is required for the initial crack of the shell.

The first embodiment of the pre-sheller (1) of the invention, shown in Figures 1 and 2, breaks up the shell of a pecan nut prior to it entering a conventional sheller far more comprehensively and consistently than what is possible with a conventional side impact cracker.

The principal method by which this is achieved using the pre-sheller (1) of the invention, is to induce cracking of the shell fully around the ovoid-spherical shape of the nut on its longitudinal side surface by means of a series of profiled, rotating rollers within the pre-sheller (1). From there the cracked nuts can be further processed by means of a conventional sheller to remove broken pieces of shell and expose the fully intact kernel halves.

As an optional alternative, the pre-sheller (1) of the invention may also be used between a conventional cracking step and a conventional shelling step, in which case a conventional cracker will induce some cracking of a nut, and the pre-sheller (1) of the invention will induce full cracking around the longitudinal side surface of the nut.

The preferred embodiment of the nut pre-sheller (1) according to the invention includes a frame (2) having first (3) and second (4) ends with a set of three rollers (5) rotatably mounted between the first (3) and second (4) ends of the frame (2). The longitudinal axes of the rollers (5) are substantially co-axially aligned and positioned in a triangle for the rollers (5) to provide a passage (6) extending from the first end (3) to the second end (4) of the frame (2) between adjoining surfaces of the rollers (5).

The pre-sheller (1) is provided with drive means in the form of an electric motor (not shown). The motor is connected by means of a chain (not shown, for the sake of clarity) to the free end (8A) of the axis (9A) of one the rollers (5A), where it extends from the first end of the frame (2). The chain engages a first gear (10A-1) at the end of the axis (9A).

The free ends (8B, 8C) of the other two rollers (5B, 5C) are connected by another chain (not shown) to a second gear (10A-2) on the free end (8A) the first roller (5A). The free ends of the axes (9B, 9C) of the second and third rollers (5B, 5C) are each provided with a gear (10B, 10C) which engages the second chain that extends around the second gear (10A-2) on the free end (8A) the first roller (5A). The motor rotates the rollers (5) all in the same direction.

The opening of the passage (6) at the first end (3) of the frame (2) is configured as an inlet (11) to the frame (2) and thus to the pre-sheller (1) and the opening of the passage (6) at the second end (4) of the frame (2) is configured as an outlet (12) from the frame (2) and thus the pre-sheller (1).

The passage (6) is configured with a taper from the first end (3) to the second end (4) of the frame (2). This is achieved by each roller (5) having an increasing diameter from the first end (3) to the second end (4). The gap between the three rollers (5) is determined by the outer diameter and pitch line center distance of the three rollers (5).

This gap provides a predeterminable cross-sectional area perpendicular to the longitudinal axes (9) of the rollers (5), with the area being sized to allow a pecan nut within a predetermined size range to enter the inlet (11) only with its longitudinal axis substantially perpendicular to the cross-sectional area of the passage (6) at its inlet (11), and to travel through the passage (6) in this orientation. This is further aided by providing a cover plate with a circular aperture (11) to form the inlet to the passage (6), as shown in Figure 1. This inlet aperture (11) is sized according to the size range of pecan nuts to be processed.

In use, a feedpipe is secured over the inlet (11) and this may be fed with pecan nuts from a hopper arrangement (not shown). The nuts are rolled around their longitudinal axes between the rollers (5) to crack the shells of the nuts, and the cracked nuts exit the pre-sheller (1) from the outlet (12).

As mentioned above, the passage (6) is sized to process pecan nuts within a predeterminable size range having a minimum and a maximum diameter and at least a minimum length. In this preferred embodiment the pecan nuts may be pre-sized according to their diameters in increments of between 1.5mm and 2mm.

The mean diameter of the passage (6) at the inlet (11) is larger than the largest diameter and smaller than the minimum length of a pecan nut that is pre-sized to be within the size range. This allows any pre-sized pecan nut to be received longitudinally into the passage (6) through the inlet (11), but the inlet size prevents such sized nuts to transversely enter the passage (6) at the inlet (11). This arrangement therefore forces each nut to move through the passage (6) end-to-end (longitudinally) and prevents each nut from turning sideways (transversely).

Furthermore, the mean diameter of the passage (6) at a position between the inlet (11) and the outlet (12) is smaller than the smallest diameter of any such pre-sized pecan nut. This ensures that each such pre-sized pecan nut that moves through the passage (6) is subjected, at some point within the passage but not deeper than the point described above, to a rolling compressive force between the rollers whilst it is supported in at least three points along its circumference.

Rotation of the rollers (5), in the same direction, rotates nuts within the passage (6).

The rollers (5) are profiled, with each roller (5) being provided with a helical rib (not shown) that extends from its top, and the first end (3), to its bottom at the second end (4). The helical ribs are spaced apart far enough to not interfere with each other. The helical ribs are arranged so that rotation of the rollers (5) forces the nuts from the inlet (11) to the outlet (12).

The profiles on the rollers (5) achieves the following:

• It induces downward momentum into the tapered rollers (5),

• It creates rotational movement on the nuts to promote even cracking of their shells on all sides.

This movement forces each nut into an ever-decreasing cross sectional area whilst applying relatively equal force around the total diameter of the shell of the nut, and with the shell and rollers (5) being in contact at any given time in at least three contact points.

The contact in at least three positions ensures that the nut is compressed by the rollers (5) with enough force, which is distributed evenly enough, to crack the shells of the nuts around their circumferences.

In a second embodiment of the invention (20) shown in Figures 3 and 4, the configuration of using 3 rollers is expanded by adding additional rollers to form a bank (20) of rollers (21), with each set of 3 rollers in the bank (20) creating a passage (22) between them. In this second embodiment of the invention, a set of nineteen rollers (21) are combined in two rows (23, 24) of rollers to create 17 passages (22). A first row of rollers (23) has ten rollers (21 A), and the second row (24) has nine rollers (21 B). The rollers of the second row (24) are arranged to be aligned with the gaps between rollers in the first row (23).

The passages (22) are fed by nuts that are placed in a hopper (25) above them. The hopper (25) includes a plurality of outlets (26), each of which feeds into one of the passages (22).

The various rollers (21) in this bank of rollers (20) are connected by means a drive belt (not shown for the sake of clarity) operating drive gears (27) on each roller, to rotate all the rollers

(21) at the same speed. The rollers (21) are driven by a single electrical motor (28).

Using the rollers (21) in this manner provides economy of scale. A set of 3 rollers, as shown in Figures 1 and 2, has one passage (6). Each additional roller that is added to the configuration adjacent the original set of 3 rollers, adds another passage to treat nuts. Therefore, adding one extra roller doubles the number of passages from one to two. Adding two rollers triples the number of passages from one to three. Adding three extra rollers increases the number of passages from one to four. In this manner, nineteen rollers (21) provide seventeen passages

(22). This modularity of the pre-sheller of the invention allows for a very cost-effective expansion of production capacity to meet production demand.

To further increase the capacity several of these banks (20) can be placed adjacent each other in one mega bank, for example with six of the roller banks (20), each one fed with its own hopper (25). Such a configuration has 114 rollers in six banks with 102 passages in total. It can treat nuts at a rate of at least 2500 kg/h.

In use, each bank of rollers (20) will be sized to treat a specific range of nut sizes. In a typical production scenario, a processer of nuts typically receives nuts from the same farms every season, and the sizes of nuts from a specific area are typically relatively consistent. This allows a nut processor to install a pre-sheller bank with a predetermined size range configuration, that can be used on such nuts.

If the size range is too broad for what can be processed in the one pre-sheller bank, then a second pre-sheller bank with a different size setting can be acquired and used for those nuts. Exchanging one pre-sheller or one pre-sheller bank for another is a simple process of disconnecting the pre-sheller or pre-sheller bank, as the case may be, from the drive, moving it out of the way and inserting the other pre-sheller or pre-sheller bank, as the case may be, in its place. This can be achieved in relatively short time, and apart from connecting and tensioning the drive belt, there is no additional setup required.

As mentioned above, the pre-sheller (1) or pre-sheller bank (20) is used as part of a nut processing system. In this system, the following general processing steps are applied:

• Dried, sized, raw pecan nuts in-shell are washed and steamed for a period of 10 minutes.

• The nuts are then fed individually through the pre-sheller (1) or pre-sheller bank (20).

• Excess broken shell is removed through an aspirator and/or vibrating screen.

• The nuts are then fed into a sheller and are further processed.

Also as mentioned above, a conventional cracker may also be sued before processing the nuts in the pre-sheller (1) or pre-sheller bank (20). In such a case, the following step will precede the pre-sheller step:

• Nuts are pre-cracked through a side-impact cracker to create minimal cracks on the surface of the shell.

It will be appreciated that the embodiments described above are given by way of example only and are not intended to limit the scope of the invention. It is possible to alter aspects of the embodiments without departing from the essence of the invention.

It is for example possible to change the angle of the axes (9) of the rollers (5) relative to each other between the first (3) and second (4) ends of the frame to achieve the taper between the rollers (5).

It is also possible to use more than 3 rollers, for example 4 or 5 rollers or in a bank such as shown with the pre-sheller bank (20). More rollers provide more contact points which is expected to only improve the effectiveness of the cracking of the nuts in the pre-sheller.

It is also possible to use less than 3 rollers, for example 1 or 2 rollers. In an embodiment where only 1 roller is used, a cover would be arranged partially around the roller between the first and second ends of the frame. The cover will be shaped to provide a passage between it and the roller, and the nuts will be fed into the passage for cracking. This passage could have a linear orientation between the first and second ends of the frame, or it could be shaped in a helix around the roller to increase the path length.

In an embodiment where 2 rollers are used, a cover between the first and second ends of the frame will also provide an additional surface to form the passage for the nuts. In this embodiment the nuts will be cracked in the nip of the two rollers with the cover containing them.

In the embodiments described above where more than one roller are used, one, some or all the rollers may be driven. Where rollers are not driven, they may be linked to the driven roller by a drive link such as a chain, or they may be freely rotatable. The choice of configuration in respect of this will be dictated by the characteristics of the type of nuts that is being cracked.