EP0922639A2

EP0922639A2 - Egg handling system

Info

Publication number: EP0922639A2
Application number: EP98306686A
Authority: EP
Inventors: Michael John Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-08-21
Filing date: 1998-08-20
Publication date: 1999-06-16
Also published as: GB9717902D0; EP0922639A3

Abstract

An egg handling system comprising an inclined shaker tray 20 supplied with eggs and a row of delivery stations 28 at the bottom edge of the tray, each for receiving an egg from the tray and having release means 32,33 for releasing the egg. Delivery station control means (a timer, or an alignment sensor) ensure that the egg in the delivery station is aligned before the egg is released. The eggs roll down a slight incline to the bottom edge of the tray, which by the manner of its oscillation aligns the eggs. The exit of the eggs from the delivery station may be controlled to rotate the egg in a direction dependent on its orientation so as to orient the egg into a predetermined orientation, or the eggs can be directed to two different cassettes in dependence on their orientation.

Description

The present invention relates primarily to an egg handling system, that is, a system for the location, orientation and moving of eggs. However, it also has applicability to the handling of egg-like items such as confectionery eggs (which may or may not have a pointed end), certain types of fruit such as lemons, and other items.
Nature has designed the egg so that it will not roll easily in a straight line. This, and their delicate nature, means high speeds of automated processing are difficult to achieve reliably. The eggs involved may be either real eggs (usually hens' eggs) or types of confectionery eggs.
The shape of an egg is that of a somewhat pointed oval rotated about its long axis. The egg is slightly conical or tapered so that it has a big end and a little end; all sections of the egg perpendicular to the axis are circular. We shall describe an egg with its axis lying along a particular desired direction as aligned. An aligned egg may have its big end pointing either way along the chosen alignment axis; we shall describe an egg which is pointing in a particular desired one of these two ways as oriented.
The eggs, from collection or production, are usually transferred by conveyor belt, and are randomly positioned. They must then be so manipulated that every egg's alignment may be defined, and preferably their orientation also, so that they may then be processed further, such as being wrapped or packed.
One such machine which attempts to do this has the eggs transferred from the conveyor belt to a belt of rotating rollers. When an egg reaches the end of the conveyor belt, paddles protruding from between the rollers lift the egg onto the roller belt, and the paddles withdraw as the belt progresses. The rollers all rotate in the same sense, so the egg between the rollers rotates (in the opposite sense); this rapidly aligns the eggs. Since an egg tilts downwards slightly at its pointed end, the eggs move to one or other side of the belt of rollers, depending on the alignment of the egg. Eggs on one side of the belt of rollers are flipped over by a protruding flange and air blast arrangement and travel back to the other side, so that all the eggs are now on the same side of the belt, and have the same orientation. They are constrained on this side by a location groove, formed by a narrowing on each roller.
The eggs are transferred to an indented belt by a double wheel arrangement. That is, a wheel equipped with closing jaws picks the eggs from the rollers, and a further wheel, with jaws which are perpendicular to those of the first wheel, picks the eggs from the jaw of the first wheel. The second wheel then releases the eggs over the indented nests of an indented conveyor. From here the eggs are now precisely located and may have further operations performed on them.
The difficulties with this system occur at the very beginning. The conveyor belt feeding the roller belt must have a width constriction guide placed above it so that only one egg at a time is offered to the protruding paddle, but at high speeds this means that only about half the paddles actually pick up an egg. Since each part of the system from here exactly coincides, only about half the nests of the final conveyor will be occupied.
The general object of the present invention is to provide an improved method for positioning and orienting eggs on a production line.
According to the invention there is provided an egg handling system comprising an inclined tray supplied with eggs and a delivery station at the bottom edge of the tray for receiving an egg from the tray and having release means for releasing the egg, characterized by delivery station control means for ensuring that the egg in the delivery station is aligned before the egg is released.
The tray is intended to align the eggs into a standard alignment before they enter the delivery station. However, the eggs on the shaker tray may interfere with each other, or individual eggs may roll down it rapidly without such alignment being achieved. The control means are provided for further ensuring that if an unaligned egg (ie an improperly aligned egg, one aligned at an angle to the desired alignment) enters the delivery station, it becomes aligned before being released.
An unaligned egg in the delivery station may be aligned either by slightly shaking the delivery station (preferably permanently rather than in dependence on detection of lack of alignment) or by allowing the egg in the delivery station to contact an egg on the shaker platform and so be slightly shaken.
A timer may be used to hold the egg in the delivery station for a time which is long enough to ensure that the chance of the egg remaining unaligned after that time is negligible. Preferably, however, sensing means (together with suitable processing means, such as a microprocessor and associated memory, or suitable dedicated logic circuitry) are provided for sensing the alignment of the egg on the delivery station, with the egg being retained until proper alignment is sensed. The delivery station preferably includes entry means (which may comprise a mechanical flap or a pneumatic barrier) for controlling the ingress of eggs, so that once the egg in the delivery mechanism is aligned, the entry of the next egg is held off until after the release after the current egg has been released.
The delivery station may well feed a mechanism which imposes restrictions on the time at which the egg is released. For example, it may feed a conveyor with defined pockets or locations for receiving the eggs, or it may feed a carton or cassette with a plurality of egg receiving locations which have to be brought into position one after the other. In such circumstances, the operation of the release mechanism will of course be further delayed until the egg receiving position is properly located with respect to the delivery station.
The system preferably has means for shaking the tray sideways. The eggs may be delivered to the top edge of the tray by a conveyor belt. After the eggs leave the belt, they roll down a slight incline to the bottom edge of the tray, which by the manner of its oscillation aligns the eggs, although of course some eggs will be oriented in the opposite direction to others. When the reach the bottom edge of the tray, they enter the row of delivery stations. Means may be provided for sensing the number of eggs on the tray and controlling the flow of eggs to the tray in dependence thereon.
The delivery station may include exit chute means shaped so as to automatically rotate the egg in a direction dependent on its orientation so as to orient the egg into a predetermined orientation. Alternatively, it may include means for sensing the orientation of the egg, with the release means including means settable in dependence on that orientation to rotate the egg so as to orient it into a predetermined orientation. Thus the chute may be moved transversely to one or other of two positions, or a pair of oppositely chutes may be provided, with the appropriate one being moved below the delivery mechanism. Alternatively, suitable flaps may be provided in the chute and operated in dependence on the orientation of the egg, or the release means of the delivery station may be operable in two different ways, depending on the egg's orientation.
As an alternative to orienting all the eggs to the same orientation, they may be retained in their two different orientations and directed to one or other of two separate cassettes or the like accordingly.
Preferably there is a row of delivery stations along the bottom edge of the tray. Dividers may be provided on the tray between the egg delivery stations, attached to the tray and/or the egg delivery stations.
The system may include an output transport mechanism comprising an intermediate conveying means, an acceleration belt, and a cassette loading system. Alternatively, it may include an output transport mechanism comprising means for feeding the eggs substantially directly into one or more cassettes.
An egg handling system embodying the invention and various modifications thereof will now be described, by way of example, with reference to the drawings, in which:
Fig. 1 is a general end viw of the system;
Fig. 1a is a side view of part of the Fig. 1 system;
Fig. 2 is an side view of another part of the Fig. 1 system;
Fig. 3 is an side view of another part of the Fig. I system;
Figs. 4 and 4a are side and top views of a modification of part of the Fig. 1 system.
The system shown in Fig. 1 comprises an inclined tray 20, a set of delivery stations each including release means comprising a drop door assembly 28, a belt 40, an egg acceleration assembly 60, and a line of cassettes 70 mounted on a chain belt 74.
The eggs to be arranged arrive on, for example, a conventional conveyor belt (not shown), and roll on to the inclined tray 20. The tray is mounted on sliding guides 22 by which the tray is subjected to a side-to-side oscillation. The eggs align their axes horizontally, in parallel with the lowest edge of the tray, and roll down the tray to the lower edge thereof.
The oscillation has a frequency of about 1 to 2 Hz and an amplitude of 2 to 3 mm. The actual values may be adjusted by observation until the most effective oscillation is found. It has been found that under the influence of the oscillation, the eggs align themselves parallel to the direction of oscillation, undergoing an end-to-end rocking motion; if an egg is aligned transverse to the oscillation and rolling to and fro, its axis rapidly rotates into alignment with the oscillation.
The inclined side edges of the tray each include a wall 25, 26 to prevent the eggs falling off the sides. Photodiodes 24 may be incorporated along the walls to give an indication of the level on the tray that the eggs have reached. This indication can be used to suspend the delivery of further eggs to the tray, since with eg confectionery eggs the eggs may fret against each other and become damaged if they spend too long on the tray. (A light source such as an LED is of course required for the photodiodes; with suitable optical arrangements, a single light source may be used for several photodiodes.)
The egg delivery assembly consists of a row of egg delivery stations 28 arranged along the bottom edge of the oscillating tray. The egg delivery assembly does not oscillate, and so the relative movement between the tray and the egg delivery assembly helps any eggs not already lying aligned (that is, with their axes horizontal) to be forced horizontal.
There are 8 egg delivery stations along the egg delivery assembly, and of course this will determine the width of the tray. Dividers are preferably provided on the tray between the egg delivery stations, to separate the incoming undifferentiated stream of eggs into 8 streams for the 8 egg delivery stations. Each divider can conveniently be dart or wedge shaped, with its tall end adjacent to the egg delivery assembly and sloping down to a point at its other end. Each divider may be fixed either to the egg delivery assembly, or to the tray, or attached to both (with its point hinged to the tray, the top of its tall end to the egg delivery assembly, and the bottom of its tall end to either the egg delivery assembly or the tray). A divider mounted solely on the tray can be regarded as a rib; it is possible to use ribs in combination with dividers mounted partly or wholly on the delivery assembly.
Each egg delivery station has a piston 30, a pair of drop doors 32 and 33, and a photodiode 34. When an egg rolls off the tray and occupies a station in the delivery station assembly, its presence is detected by the egg cutting the beam between the photodiode and its light source. The piston is then pneumatically activated to block the progress of eggs above the position until the delivery station is free. The piston is positioned to miss the egg in the delivery station even if the egg is aligned vertically.
For optical detection, the optics can be separated from contact with the eggs at the ends of suitable light paths. The light paths may be formed of suitable transparent materials, so that they leave the surfaces which the eggs come into contact with as mechanically smooth. Alternatively, open (air) light paths may be used, with the light paths preferably being slightly conical with the narrow ends adjacent to the eggs, so that stray bits of eggs falling into the light paths won't get stuck.
At an appropriate moment, the drop doors open allowing the egg to drop, and after a suitable time interval the drop doors close and the piston is withdrawn to let another egg roll into the delivery station. The drop doors may be hinged at their outer edges to rotate downwardly and outwardly, or may be mounted to slide apart horizontally.
Rather than a piston, other methods of regulating the falling of eggs into the delivery station may be employed, such as an air jet or paddle wheel above each station. Additionally, the photodiode could be replaced by another system to check the occupancy of the location such as a weight detection device.
When an egg enters a delivery station, it is desirable to allow a dwell or settling time before attempting to release it from the station. If an egg enters the station misaligned, this will give the egg a further chance to become correctly aligned. For this, some sort of oscillation must be applied to the eggs in the delivery stations. This can be achieved by oscillating the delivery station assembly slightly. Alternatively, by suitable design of the piston, the following egg may be allowed to remain in contact with the egg in the station. (The following egg is, of course, on the oscillating tray and is therefore itself oscillating.) Further, the doors of the delivery station may be curved to promote correct settling of the egg. The photodiode, or a plurality of photodiodes, can be arranged to detect when the egg is aligned horizontally.
The system thus both detects the presence of an egg in the delivery station and ensures that only a single egg is present in the station, both of these characteristics being important.
Beneath the delivery station assembly is a belt 40, running beneath the entire length of the assembly, and having dividers or flights 42 mounted thereon. The eggs are dropped through the drop doors with suitable timing to fall between the flights of the belt and are conveyed along by the belt. Against one side of the belt is a wall 44, and a similar wall 45 is situated on the other side of the belt. The walls against the belt and the flights serve to maintain the eggs aligned parallel to the belt. The belt may also be formed with hollows (not shown) aligned parallel to its length, to hold the eggs in their alignment.
The belt is driven by a pair of wheels or sprockets 47, 48 in a conventional manner from underneath, so that in the drawing it travels in an anticlockwise sense. A single photodiode 50 is placed immediately before the belt is actually beneath the delivery station assembly, and is at such a height that the beam between the pair is tripped by the belt flights. Since the speed of the belt is known, the dropping of eggs onto the belt can be timed to coincide with a free position between the flights. Using the data from the drop door location photodiodes and the single photodiode triggered by the belt flights, a processor can be used to operate the drop doors to ensure that a single egg is dropped in every location on the belt.
As a further check of the occupancy of the flighted belt, groups of photodiodes 52 are positioned in the banks either side of the belt, and this data is also fed to the control unit. Thus if there is an empty position on the belt, the next available delivery station can be operated to try to fill it; and if that attempt should fail (eg by the egg becoming stuck in the delivery station), another delivery station further along the assembly can be tried, and so on. This will result in a very high belt occupancy rate, very close to 100%, because repeated attempts can be made to fill an empty position; also, the egg flow rate through the delivery stations towards the end of the assembly will be low, so the eggs in those stations will have a long settling time and those stations will therefore have a very high delivery reliability.
The eggs from the flighted belt are then fed to the acceleration assembly 60, prior to being inserted into the cassette 70. The acceleration assembly contains four belts 62, 63, 64, and 65 in a cruciform arrangement as shown in Fig. 3. The speed of these belts is significantly faster than that of the flighted belt, so that the time necessary for the cassette to remain stationary whilst the egg is being loaded is reduced. This allows the cassette more time to move on one position for the next egg to be loaded.
The cassette consists of a bar through which 12 holes 71 have been bored. The bore diameter is such that whilst an egg can fit in the hole, it is not able to turn. To achieve more compact packing, the holes are bored so that their circumferences overlap, whilst still completely constraining the egg. The holes may widen towards the surface of the bar to assist loading. The cassette is moved downwards in a stop-start fashion to coincide with the loading of the eggs. The movement may be synchronized by the photodiode triggered by the belt flights, or a further photodiode may be included to check the egg's location prior to being loaded onto the cassette.
It is possible that at high speeds not every location on the belt has been filled; if this occurs, the control unit can be used to detain the cassette for the duration of the gap so that the cassette will be fully loaded.
Referring to Figure 2, the cassette 70 is contained vertically within a shaft (not shown) and supported by a spacer block 72. Part of the shaft includes a cushioned area so that though the egg is contained in the hole by the shaft when loaded, it will not be damaged. The spacer block is joined between links of a chain belt 74, which is driven by a pair of sprockets 75, 76, thus moving the entire cassette. Spacer blocks are interspersed at regular intervals along the chain, so that a series of cassettes can be moved past the acceleration belt assembly to be loaded. Depending on the dimensions of the spacer block, an extra distance must be moved after each cassette is filled.
A loaded cassette may then be enclosed between two strips of metal, so that the eggs may be easily transferred without their alignment changing. Loaded cassettes may be placed side by side between two retaining sheets, forming a buffer so that further production processes may be continued if the egg handling machine has to be temporarily closed down for maintenance. The cassette could also have the holes bored so that the cavities so formed do not extend through the entire bar, so that the eggs may be transported on an automated line simply by ensuring the cassettes' holes are facing upwards. If the hole does extend through the bar, the cassette may be moved on a conveyor belt, the belt surface containing the eggs, and the eggs may be easily released by sliding the cassette over a flat surface with an aperture for the eggs to drop through.
Once the eggs have had their axes aligned at the delivery station assembly, and can be released in an orderly fashion through the drop doors, they are much easier to handle, and consequently different types and combinations of mechanisms may be substituted for conveying the eggs after they have left the drop doors. For instance, a jawed wheel could be used to pick up the eggs from the flighted belt and deposit them on an indented conveyor with nest positions, as in the prior art. Instead of a flighted belt, an indented belt with nest positions, or a helical auger with guides could be used to convey the eggs from beneath the drop doors.
The cassettes may be located directly beneath the drop doors so that the eggs are released directly into the cassettes' cavities. But since the cassettes are designed for eggs' axes to be aligned with the holes" axes, the drop door mechanism must be altered, as shown in Fig. 4, so that the eggs are turned through 90° as they fall from the drop doors. Rather than the doors 32, 33 being hinged, they slide apart horizontally to allow the egg to fall from the aperture. One door has a tongue 36 which constricts the aperture when the doors have fully opened, which causes the egg to turn as one end catches on the tongue.
Although the data from the drop door photodiodes and the photodiode triggered by a cassette breaking its beam (in the same manner as the belt flights synchronising the dropping of eggs as described above) should ensure that the cassettes may be completely filled, the arrays of photodiodes beneath the drop doors may be used to check occupancy. For this, small holes are bored across the cassettes, permitting the beam to penetrate a cassette if an egg is not present in the cavity. Alternative arrangements of doors which achieve the same result are possible, such as a single hinged or sliding door, or single door and fixed shelf, to turn the egg by 90°.
In the arrangements discussed so far, the system has aligned the axes of the eggs and enabled their position to be accurately defined, but each egg may still be pointing in one of two directions (ie unoriented), when ideally the eggs should all be oriented (pointing) in the same direction for further processing.
One solution is to simply have the eggs leaving the drop doors dropped on the belt of rollers discussed in the prior art system. A system such as this would now achieve a full occupancy of the positions available between the rollers, and then the rollers would ensure the eggs were pointing in the same direction.
It is however preferred to incorporate an orientation device within the drop door assembly so that higher speeds may be reached with less discrete devices. This requires either some means of detecting the orientation of the egg, or a drop arrangement in which the orientation of the egg automatically causes the egg to rotate to a standard orientation.
A convenient way of detecting the orientation of the egg is by an array of photodiodes of sufficient resolution and feeding suitable shape recognition software. This may require a set of say 6 or so photodiodes, arranged so that the alignment of the egg is first detected and confirmed, and then when the egg is accurately aligned, its orientation is detected.
A suitable arrangement of drop doors, such as two hinged doors supporting respective ends of the egg, may be operated by opening of one door whilst the other remains closed. This will result in the egg turning by +90° or -90° as it falls, depending on which door is opened. The egg may thus oriented so that it points upwards or downwards as desired.
An alternative arrangement is to have two extendable tongues beneath two sliding drop doors so that the appropriate tongue may be extended beneath the opening doors to turn the egg one way or the other. If the egg can be placed in the drop door location so that its centre of gravity always occupies the same position, the two short permanent shelves can be so positioned so that one always delays the pointed end of the egg, this end being a greater distance from the centre of gravity than the blunt end, and so the egg always falls so as to be pointed upwards.
In either case, a chute may be provided to help to constrain the egg's path sand ensure that it rotates correctly. It will usually be desirable for the chute to be mounted so that it can be moved between two positions, one for each of the orientations of the egg in the delivery station.
Depending on which way the egg is made to turn, it will follow one of two trajectories, and so land on the conveying means below in one of two positions. If the conveying means is a flighted belt or a cassette being drawn below all the drop doors, dropping the eggs into the correct position may be achieved by adjusting the moment when the drop doors are opened depending on which way the egg is to fall. A further method is to provide a guide beneath the drop doors to constrain the egg's trajectory so that the two possible trajectories on leaving the chute are brought together into a common path independent of which way the egg has been turned.
In place of the belt arrangement described above, the eggs can be delivered from the delivery stations direct into a cassette. For this, the cassette is preferably movable parallel to the line of delivery stations, and there are preferably a few more delivery stations (say 14) that there are receivers in the cassette (say 12). Thus a cassette will normally be placed under the first 12 delivery stations and have all its receivers filled simultaneously, but if one or two receivers are not filled, the cassette can be moved along to use the last two delivery stations.
An alternative method is to have 12 cassette lines, one line of cassettes being drawn beneath each delivery station, the cassette lines being mounted on horizontal sliding guides perpndicular to the direction in which they are drawn so that the position of each cassette may be altered depending on which way the egg is to be turned.
Another option is to have the cassette movable in 2 dimensions, so that it can be stepped perpendicularly to the delivery station assembly for filling and then along the axis of the assembly (and possibly backwards as well) in case any receivers are not filled.
This system can easily be adapted for use with objects having a different shape where it is required that these objects have their positions, and when asymmetrical, their orientations constrained. Such objects may for example be balls, skittles, bottle stoppers, bolts or pills, and upon reflection many other objects will present themselves as suitable, requiring only a change in the devices' dimensions, and an alteration of any shape recognition software.
In summary, there is thus provided an egg handling system comprising an inclined shaker tray 20 supplied with eggs and a row of delivery stations 28 at the bottom edge of the tray, each for receiving an egg from the tray and having release means 32,33 for releasing the egg. Delivery station control means (a timer, or an alignment sensor) ensure that the egg in the delivery station is aligned before the egg is released. The eggs roll down a slight incline to the bottom edge of the tray, which by the manner of its oscillation aligns the eggs. The exit of the eggs from the delivery station may be controlled to rotate the egg in a direction dependent on its orientation so as to orient the egg into a predetermined orientation, or the eggs can be directed to two different cassettes in dependence on their orientation.

Claims

An egg handling system comprising an inclined tray (20) supplied with eggs and a delivery station (28) at the bottom edge of the tray for receiving an egg from the tray and having release means (32,33) for releasing the egg, characterized by delivery station control means for ensuring that the egg in the delivery station is aligned before the egg is released.
An egg handling station according to claim 1 characterized in that the control means comprise a timer which ensures that a minimum settling time is allowed before the egg is released.
An egg handling station according to claim 1 chraracterized in that the control means comprise sensing means for sensing the alignment of the egg on the delivery station.
An egg handling station according to any previous claim characterized in that the delivery station includes entry means (30) for controlling the ingress of eggs.
An egg handling system according to any previous claim characterized by means for shaking the tray sideways.
An egg handling system according to any previous claim characterized by means (24) for sensing the number of eggs on the tray and controlling the flow of eggs to the tray in dependence thereon.
An egg handling system according to any previous claim characterized in that the delivery station includes exit chute means shaped so as to automatically rotate the egg in a direction in dependence on its orientation so as to orient the egg into a predetermined orientation.
An egg handling system according to any of claims 1 to 7 characterized in that the delivery station includes means for sensing the orientation of the egg and in that the release means include means (Figs. 4,4a) settable in dependence on that orientation to rotate the egg so as to orient it into a predetermined orientation.
An egg handling system according to any previous claim characterized in that there is a row of delivery stations (Fig. 1) along the bottom edge of the tray.
An egg handling system according to claim 9 characterized by dividers provided on the tray between the egg delivery stations, attached to the tray and/or the egg delivery stations.
An egg handling system according to any previous claim characterized by an output transport mechanism comprising an intermediate conveying means (40), an acceleration belt (60) , and a cassette loading system (60,76).
An egg handling system according to any of claims I to 10 characterized by an output transport mechanism comprising means for feeding the eggs substantially directly into one or more cassettes.
Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International Convention (Paris Convention).