WEIGHING APPARATUS AND METHOD FOR WEIGHING FOOD PRODUCT

Abstract

A weighing apparatus for weighing batches of food product is provided. The weighing apparatus comprises a product supply unit arranged to supply food product to be weighed, a weighing unit arranged to receive and weigh a batch of food product, and a product delivery unit arranged to receive the food product from the product supply unit and to deliver a batch of food product to the weighing unit. The product delivery unit comprises a trough extending between a product supply position, at which food product is received from the product supply unit, and a product delivery position, at which the food product is delivered for receipt in the weighing unit, and a transport screw arranged in the trough and configured to rotate in the trough for conveying food product from the product supply position to the product delivery position. The transport screw comprises at least two helical members. A primary helical member extends along a length of the trough substantially from the product supply position to the product delivery position. A secondary helical member extends along a length of the trough substantially from the product supply position to a termination position of the secondary helical member, the termination position of the secondary helical member being between the product supply position and the product delivery position.

Claims

1. A weighing apparatus for weighing batches of food product, the weighing apparatus comprising: a product supply unit arranged to supply food product to be weighed; a weighing unit arranged to receive and weigh a batch of food product; and a product delivery unit arranged to receive the food product from the product supply unit and to deliver a batch of food product to the weighing unit, the product delivery unit comprising: a trough extending between a product supply position, at which food product is received from the product supply unit, and a product delivery position, at which the food product is delivered for receipt in the weighing unit; and a transport screw arranged in the trough and configured to rotate in the trough for conveying food product from the product supply position to the product delivery position; wherein the transport screw comprises at least two helical members, wherein a primary helical member extends along a length of the trough substantially from the product supply position to the product delivery position and wherein a secondary helical member extends along a length of the trough substantially from the product supply position to a termination position of the secondary helical member, the termination position of the secondary helical member being partway between the product supply position and the product delivery position.

2. A weighing apparatus according to claim 1, wherein the primary helical member and/or the secondary helical member has a constant radius of curvature.

3. A weighing apparatus according to claim 1, wherein the primary helical member and the secondary helical member have substantially the same radius of curvature between the product supply position and the termination position of the secondary helical member.

4. A weighing apparatus according to claim 1, wherein the primary helical member and/or the secondary helical member has a constant pitch, or a pitch that increases towards the product delivery position.

5. (canceled)

6. A weighing apparatus according to claim 1, wherein the primary helical member and the secondary helical member have substantially the same pitch between the product supply position and the termination position of the secondary helical member.

7. A weighing apparatus according to claim 1, wherein the secondary helical member is arranged substantially coaxial to the primary helical member.

8. (canceled)

9. A weighing apparatus according to claim 1, wherein the termination position of the secondary helical member is at a position at a distance from the product supply position to the product delivery position selected from the group consisting of between 10% and 90% between 20% and 80%, between 30% and 70%, between 40% and 60%.

10. A weighing apparatus according to claim 1, wherein the transport screw comprises first and second primary helical members, wherein each primary helical member extends along a length of the trough substantially from the product supply position to the product delivery position.

11. A weighing apparatus according to claim 10, wherein the first and second primary helical members have substantially the same radius of curvature, pitch and/or length.

12. A weighing apparatus according to claim 10, wherein the first and second primary helical members are substantially coaxial.

13. (canceled)

14. A weighing apparatus according to claim 1, wherein the transport screw comprises first and second secondary helical members, wherein the first secondary helical member extends along a length of the trough substantially from the product supply position to a termination position of the first secondary helical member and wherein the second secondary helical member extends along a length of the trough substantially from the product supply position to a termination position of the second secondary helical member, the termination positions of the first and second secondary helical members being between the product supply position and the product delivery position.

15. A weighing apparatus according to claim 14, wherein the first and second secondary helical members have substantially the same radius of curvature and/or pitch.

16. A weighing apparatus according to claim 14, wherein the first and second secondary helical members are substantially coaxial.

17. (canceled)

18. (canceled)

19. A weighing apparatus according to claim 1, wherein the transport screw further comprises a core positioned inside the primary and secondary helical members.

20. A weighing apparatus according to claim 1, wherein rotation of the transport screw comprises rotation of the primary and secondary helical members about their longitudinal axes.

21. (canceled)

22. (canceled)

23. A weighing apparatus according to claim 1 the primary and secondary helical members are each open along their central axis.

24. (canceled)

25. (canceled)

26. (canceled)

27. (canceled)

28. A weighing apparatus according to claim 1 comprising a plurality of weighing units, each arranged to receive and weigh a batch of food product, and a corresponding plurality of product delivery units, each product delivery unit being arranged to receive food product from the product supply unit and to deliver a batch of food product to the corresponding weighing unit.

29. A weighing apparatus according to 28, wherein the plurality of product delivery units are arranged around a periphery of the product supply unit, and wherein the product supply unit is configured to distribute product radially for receipt at the product supply position of each of the product delivery units.

30. A weighing apparatus according to claim 1, wherein the or each product delivery unit is arranged in use such that the trough is in an inclined orientation, the product supply position being higher than the product delivery position.

31. A method of weighing batches of food product comprising: supplying food product for receipt at a product supply position using a product supply unit; receiving the food product at the product supply position using a product delivery unit; delivering a batch of food product to a product delivery position using the product delivery unit; receiving the batch of food product delivered to the product delivery position in a weighing unit; and weighing the batch of food product using the weighing unit; wherein the product delivery unit comprises: a trough extending between the product supply position and the product delivery position; a transport screw arranged in the trough and configured to rotate in the trough for conveying food product from the product supply position to the product delivery position, the transport screw comprising at least two helical members, wherein a primary helical member extends along a length of the trough substantially from the product supply position to the product delivery position and wherein a secondary helical member extends along a length of the trough substantially from the product supply position to a termination position of the secondary helical member, the termination position of the secondary helical member being between the product supply position and the product delivery position.

32. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the invention will now be described with reference to the following Figures, in which:

[0024] FIG. 1 is a schematic top view of a weighing apparatus according to a first embodiment of the invention;

[0025] FIG. 2 is a schematic top view of the weighing apparatus according to the first embodiment of the invention with the supply unit omitted;

[0026] FIG. 3 is a schematic cross-section of the weighing apparatus according to the first embodiment of the invention;

[0027] FIG. 4 is a top view of a product delivery unit of the weighing apparatus according to the first embodiment of the invention;

[0028] FIG. 5 is an end view of the product delivery unit of the weighing apparatus according to the first embodiment of the invention;

[0029] FIG. 6 is a top view of a product delivery unit of a weighing apparatus according to a second embodiment of the invention; and

[0030] FIG. 7 is a top view of a product delivery unit of a weighing apparatus according to a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1 is a top view depicting the overall configuration of a weighing apparatus (this embodiment showing a type of weigher often referred to as a combination weigher) according to a first embodiment of the present invention. FIG. 2 shows the same weighing apparatus, but with the product supply unit 100 omitted to schematically depict the product delivery units 200 the weighing units 300. FIG. 3 is a side cross-sectional view of the overall configuration of the weighing apparatus of FIG. 1. The weighing apparatus includes a product supply unit 100, a plurality of product delivery units 200 arranged around and extending radially from the product supply unit 100, and a corresponding plurality of weighing units 300 at the distal end of each product delivery unit. The present embodiment shows twelve product delivery units 200; however, any number of product delivery units 200 may be used, including only one product delivery unit.

[0032] In the present embodiment, the product supply unit 100 comprises a distribution table, which has a generally cone shaped upper surface whose periphery overlaps the plurality of product delivery units. In use, food product is received on the distribution table and is directed towards the periphery by the inclined surfaces of the table. Gaps in a sidewall of the distribution table (not shown) ensure that product that falls off of the distribution table is received in a product delivery unit 200.

[0033] Each product delivery unit 200 comprises a transport screw made up of helical members 210 and 220, which will be described in more detail below. The transport screw sits in an open inclined trough 250 and rotates in the trough to convey food product radially away from the product supply unit 100. In more detail, food product that is supplied by the product supply unit is received in the trough 250 at a product supply position S, which is substantially directly below the periphery of the distribution table. The trough and transport screw extend inwardly beyond the periphery of the distribution table such that product at the product supply position S is received in the trough 250 and is immediately under the influence of the rotating transport screw. Rotation of the transport screw in the trough moves the food product in a controlled manner from the product supply position S towards the product delivery position D, at which it is urged off the end of the trough 250 and falls into the weighing unit 300. The trough and screw are arranged on an incline such that the product supply position S is higher than the product delivery position D to facilitate the delivery of the product along the trough and into the weighing unit 300.

[0034] As shown in FIG. 3, each weighing unit comprises a pool hopper 310 vertically above a corresponding weighing hopper 320. The product urged off the end of the trough 250 at the product delivery position D by the transport screw is received first in the pool hopper 310 and is temporarily retained inside the pool hoppers. The food product is then discharged from the pool hopper 310 and received in the weighing hopper 320. The food product is temporarily stored inside the weighing hopper 320, where it is weighed by load cells or other weighing means (not shown). In a combination weigher, the weights in each weigher are sent to a controller (not shown), which determines which combination of the twelve weighers contains a weight of food product that is close enough to the target weight. Those weighers are then operated to dispense the food product. The corresponding pool hoppers 310 are then operated to dispense food product into the now empty weighing hoppers 320 and the corresponding transport screws rotated to fill the now empty pool hoppers 310, at which point a new combination is determined and the cycle repeated.

[0035] Food product dispensed from the selected weighing hoppers 320 falls under gravity into a common collecting chute 300, where the multiple batches of food product are combined into a single batch with an appropriate weight and directed to a discharge position for downstream processing.

[0036] The transport screw will now be described in more detail with reference to FIGS. 4 and 5, which show the transport screw sat in the trough 250.

[0037] FIG. 4 shows that each transport screw comprises a circular support plate 260 that is rotatable about its centre by a drive shaft 265 extending from a rear surface of the circular plate and coupled to a motor (not shown). First and second helical members 210, 220 are coupled to the periphery of the circular plate 260 and extend away from the circular plate in a direction opposite to the drive shaft. The centre axis of each helical member 210, 220 is coincident with the centre of the circular plate 260 and coincident with the axis of the drive shaft 265 such that rotation of the circular plate about its centre causes the helical members to rotate about their centre axes.

[0038] The first helical member is a primary helical member 210 and extends from the circular plate 260, towards the end of the trough 250. In use, the primary helical member 210 extends through the product supply position S, at which food product is received from the product supply unit 100, substantially to the product delivery position D, which in this embodiment substantially corresponds to the end of the trough 250. The primary helical member ensures that food product is conveyed from the product supply position S to the product delivery position D.

[0039] The second helical member is a secondary helical member 220 and extends from the circular plate 260, towards the end of the trough 250. The secondary helical member is shorter than the primary helical member and terminates at a termination position T, which is approximately halfway between the product supply position and the product delivery position D. The secondary helical member 220 helps convey food product away from the product supply position S and additionally helps prevent food product from building up in the centre of the transport screw in the upstream portion of the trough 250.

[0040] Each helical member is a helical rod member and may be made of, for example, stainless steel or a suitable plastic material. In this embodiment, the primary and secondary helical members 210, 220 have the same radius of curvature and pitch of the coils that make up the helix shape. Additionally, the primary and secondary helical members 210, 220 are mounted coaxially and rotate about their common axis. Indeed, the secondary helical member corresponds 220 to a phase shifted version of the portion of the primary helical member 210 between the circular plate 260 and the termination position T. In alternative embodiments, the secondary helical member may have a smaller radius of curvature and/or may have a smaller pitch than the primary helical member to control the product handling characteristics of the transport screw.

[0041] As shown in FIG. 5, the transport screw sits in an open trough 250. The open trough comprises a lower semi-cylindrical portion 251 and two sidewalls 252. The semi-cylindrical portion 251 has an inner surface whose radius of curvature is only slightly greater than the radius of curvature of the primary and secondary helical members 210, 220 such that the screw fits within the semi-cylindrical portion of the trough and can effectively convey food product along the trough. The sidewalls 252 extend along the length of the transport screw and project upwards from the long edges of the semi-cylindrical portion 251 to ensure that product is not ejected from the trough by rotation of the transport screw.

[0042] FIG. 6 shows an alternative transport screw, suitable for use in a weighing apparatus according to a second embodiment of the invention.

[0043] This transport screw comprises a first primary helical member 210 and a second primary helical member 215. The second primary helical member is substantially identical to the first primary helical member described with respect to FIG. 4, but is phase-shifted by approximately 180 relative to the first primary helical member such that the first and second primary helical members 210, 215 together have a double helix form. As above, both primary helical member 210, 215 extend, in use, through the product supply position S, at which food product is received from the product supply unit 100, substantially to the product delivery position D, which again corresponds to the end of the trough 250 and ensure that food product is conveyed from the product supply position S to the product delivery position D.

[0044] Similarly, this transport screw also comprises a first secondary helical member 220 and a second secondary helical member 225. The second secondary helical member is substantially identical to the first secondary helical member described with respect to FIG. 4, but is phase-shifted by approximately 180 relative to the first secondary helical member such that the first and second secondary helical members 220, 225 together have a double helix form. Both the first secondary helical member 220 and the second secondary helical member 225 are the same length, and extend from the circular plate along the trough 250 to the same termination position T. It will be appreciated here that the same termination position T means same length along the trough 250, as the precise end points of the helical members will be offset from one another owing to the difference in phase of the helical members.

[0045] The two primary helical members 210, 215 are out of phase with the secondary helical members 220, 225 by approximately 90 such that each individual helical member is phase-shifted by approximately 90 compared to the adjacent helical member in the region of the trough upstream of the termination position T.

[0046] FIG. 7 shows another alternative transport screw, suitable for use in a weighing apparatus according to a third embodiment of the invention.

[0047] This transport screw differs from that described above with respect to FIG. 6 only in that the first and second secondary helical members are different lengths. More specifically, the first secondary helical member 220 extends from the circular plate 260 along the trough 250, terminating at a termination position which is a first distance along the length of the trough. The second secondary helical member 225 extends from the circular plate 260 along the trough 250, terminating at a position T.sub.2, which is a second distance along the length of the trough, greater than the distance of T.sub.1. This provides a more gradual change in surface area of the screw between the supply position, at which all four helical members are present, to the delivery position, at which only the two primary helical members 210, 215 are present.

[0048] While the embodiments of FIGS. 6 and 7 describe two secondary helical members in combination with two primary helical members, the number of primary and secondary helical members can be varied independently of one another.