WO1999057013A1

WO1999057013A1 - Method and apparatus for dosing a fluid product

Info

Publication number: WO1999057013A1
Application number: PCT/IB1999/000792
Authority: WO
Inventors: Tore SØRBY
Original assignee: Elopak Systems Ag
Priority date: 1998-04-30
Filing date: 1999-04-30
Publication date: 1999-11-11
Also published as: GB9809123D0

Abstract

Apparatus for dosing fluid product comprises a common supply conduit (1), a plurality of dosing devices (12) operating out of phase with respect to each other, and a conveyor (13) indexing receptacles (14) past the dosing devices (12). Control means controls the dosing devices (12) so that the duration of the intake action of each dosing device (12) is longer than the duration of the indexing cycle of the conveyor (13). Rotary valves (6) control the intake and delivery actions of each dosing device and are the only valves between the conduit (1) and the respective outlets of the dosing devices (12). Owing to these two features, the stress on the fluid product being dosed is greatly reduced and with high-viscosity product such as yoghurt less damage to the product occurs during dosing.

Description

METHOD AND APPARATUS FOR DOSING A FLUID PRODUCT

This invention relates to dosing methods and apparatus. EP-B-234102 discloses apparatus for filling liquid into containers comprising a filler body and a dosing device. The device communicates with the interior of a rotary valve through an end cover of the valve housing, the valve including a valve seat and a check valve closure member spring-biased towards the seat. The valve includes three rotary ports and two fixed ports. Downstream of one fixed port is an anti-drip, suck-back device of a piston-and- cylinder form whereof the stroke of the piston is adjustable. Upstream of the other fixed port is a throttling valve lowerable into an operative position downstream of inlet holes from a liquid-containing tank. For a high viscosity liquid, it is drawn into the device through the holes, that other fixed port and one of the rotary ports and the end cover, the valve is rotated to align another of the rotary ports with the one fixed port and to close the other fixed port, and the liquid is then expelled from the device through the end cover, that other rotary port and the one fixed port and an outlet nozzle. A low viscosity liquid is drawn into the device through the holes, the lowered valve, the other fixed port and the one of the rotary ports and the end cover, and is then expelled from the device through the end cover, the valve, the third rotary port and the one fixed port and the nozzle.

Such filling apparatus are normally included in a form- fill-seal packaging machine for cartons including a balance tank with liquid level control for the liquid to be filled. FR-A-2342203 discloses a system for the filling of receptacles with liquid or paste-like product from two dosing devices operating out of phase. The receptacles are advanced by means of a conveyor belt which indexes the receptacles in pairs to beneath the dosing devices. The duration of the movement period of each indexing cycle is between one-sixth and one-third of the duration of the cycle, the duration of the delivery action of each dosing device is between one- sixth and one-third of the cycle duration, whilst the duration of the intake action of each dosing device is no more than five-sixths of the cycle duration. The delivery actions of the two dosing devices may overlap each other in time and each delivery action may occur during parts of two indexing cycles. Each dosing device includes a non-return inlet valve at the entrance to its dosing chamber, and an outlet valve. The dosing devices are supplied from a product- containing reservoir via a feed conduit containing a feed pump producing a practically constant flow rate of the product. The feed conduit branches into two ducts of identical cross-section to each other and to the conduit and leading towards the respective dosing devices. There is a slide valve which is common to both ducts and is such that the total throughflow cross-section of the valve is always equal to the throughflow cross-section of one of the two ducts .

DE-A-2415237 discloses a system in which two dosing devices operating out of phase with each other deliver from a common inlet to a common outlet a substance, such as margarine, which solidifies in a state of rest. An indexing turntable brings receptacles in turn to beneath the common outlet. The delivery period of each dosing device co-incides with the dwell period of the indexing cycle. The intake duration of each dosing device is equal to the duration of an indexing cycle and the intake period extends over parts of two cycles.

Yoghurt is a high viscosity liquid; we are aware that, in the filling of yoghurt into cartons, cold filling at 3°C to 10°C is becoming the preferred method as it gives better taste/acidity owing to better control of the product temperature throughout the processing. This is particularly relevant if the cartons are loaded into roll containers, since the yoghurt in the cartons in the middle of the array on a roll container will mature at a different rate from the yoghurt in the cartons at the outside of the array.

At 3°C the viscosity is rather high, and the yoghurt structure is subject to significant damage when it passes through a filling system if it is not properly designed. Gentle handling in the filler system is important. The more gently the yoghurt is passed through the filler, the less dry additive such as milk powder or caseinate is needed to maintain the structure/viscosity of the yoghurt. Additives are a major cost of concern to the yoghurt producers.

Gentle handling means larger cross-sections in the filler system, to obtain low product velocity, while flow paths with as few bends, restrictions and expansions as possible are important to reduce the shear stress on the product. The producers would therefore prefer, if possible, to exclude the balance tank, further to reduce viscosity loss and simplify control of product supply; by excluding the balance tank, changes in through-flow cross-section into and out of the tank are avoided, as are the continual variation in through-flow cross-section of a liquid level control valve of the tank. Further, if there is no balance tank, then there is no requirement for the spray bars and special cleaning fluid supply lines and valves that are normally included for use when cleaning the balance tank. According to a first aspect of the present invention, there is provided apparatus for dosing fluid product, comprising supply means for supplying said fluid product, a plurality of dosing devices each arranged to perform, alternately, an intake action to take in said fluid product and a delivery action to deliver said fluid product, indexing means arranged to index past said dosing devices whereby said dosing devices can deliver doses of said fluid product to said indexing means, and control means for controlling said dosing devices such that said dosing devices operate out of phase in relation to each other, characterised in that said control means so controls said dosing devices that the duration of each intake action of each dosing device is longer than the duration of each indexing cycle of said indexing means. According to a second aspect of the present invention, there is provided a method of dosing fluid product, comprising supplying fluid product to a plurality of dosing devices during respective intake actions of said dosing devices, indexing receptacles past said dosing devices, dosing the fluid product from said dosing devices into said receptacles during respective delivery actions of said dosing devices, and controlling said dosing so that said dosing devices operate out of phase in relation to each other, characterised in that the duration of each intake action of each dosing device is longer than the duration of each indexing cycle of said receptacles.

Owing to the invention, stress on the fluid product being dosed can be further reduced.

This is particularly advantageous for products that are damageable by other than gentle handling, especially fermented milk products, for example yoghurt.

With the plurality of dosing devices out of phase with each other it is possible to increase that proportion of each cycle of each dosing device devoted to a suction stroke, and thereby to reduce shocks and shear stresses on the product. The dosing devices are preferably out of phase with each other to an amount equal to one nth of a cycle, where n is the number of the said dosing devices, since this arrangement gives the best potential for lengthening the time period of each suction stroke.

Advantageously, the duration of the delivery action of each dosing device is longer than the duration of each movement period of the indexing means (which is preferably in the form of a conveyor) and also the sum of the duration of the delivery action and the duration of the movement period is substantially equal to the duration of the indexing cycle of the conveyor. The dosing devices may be arranged in groups, for example in pairs, operated out of phase with each other; moreover, there may be any desired number more than one of single devices or groups of devices arranged out of phase with each other. If desired, the apparatus and method may be such that the single devices or groups of devices are operable not only out of phase with each other for products susceptible to damage, but also in phase with each other, particularly for multi-stage synchronous filling, for products not susceptible to damage.

The present apparatus and method are particularly applicable to dosing the product into receptacles, especially to filling containers, for example cartons, with the product, either with single-stage filling or multi-stage filling.

It is especially advantageous if the supply to the first and second dosing devices is by way of a supply conduit common to both devices; thereby it is possible to arrange that there is a continuous flow of product through the supply conduit and thereby more readily possible to dispense with the conventional balance tank.

There is preferably only a single valve, in particular a rotary valve, between the common supply conduit and the outlet of each dosing device.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which :-

Figure 1 shows a diagrammatic side elevation of a filling system on a form-fill-seal machine for packaging yoghurt into cartons, and

Figure 2 shows a timing diagram for parts of the machine.

Referring to the drawings, a relatively straight pipe 1 of relatively large cross-section conducts yoghurt from a cooler (not shown) to two pairs 2A and 2B of fillers 4A and

4B. Each filler 4A or 4B includes an inlet duct 5A or 5B leading from the pipe 1, a rotary valve 6A or 6B having two peripheral rotary ports co-operating with two fixed peripheral ports and also having an axial rotary port and an axial fixed port aligned with each other, a suck-back device

7A or 7B of the character disclosed in EP-A-234102, an outlet duct 8A or 8B, an outlet nozzle 9A or 9B of the character disclosed in EP-A-199538, a fluidic piston-and-cylinder device 10A or 10B for operating the valve 6A or 6B through a linkage 11A or 11B, and a dosing device 12A or 12B (hidden in

Figure 1) of the character disclosed in EP-A-287201. An indexing, endless chain conveyor 13 advances bottom-sealed, gable-top or flat-top cartons 14 in pairs A and B below firstly the filler pair 2A, where the carton pair A is filled, and then the filler pair 2B, where the carton pair B is filled. Beneath each of the filler pairs 2A and 2B, and actually below respective carton pairs thereat are respective lifters 15A and 15B, whereby bottom-up filling is performed. After filling, the cartons 14 are top-sealed.

Figure 2 illustrates the timing of the operations of the conveyor 13, the lifters 15A and 15B, the dosing device pair 12A and the dosing device pair 12B, the rotary valve pair 6A and the rotary valve pair 6B, the suck-back device pair 7A and the suck-back device pair 7B, relative to a main drive shaft (not shown) of the machine which directly operates the conveyor 13, over two revolutions of that shaft. It will be noted that the dosing device pairs 12A and 12B operate directly oppositely out of phase with each other and that more than half of each cycle of each dosing device, and thus more than a whole indexing cycle of the conveyor 13, is devoted to the suction stroke of each dosing device, whereby any shocks and shear stresses on the yoghurt being drawn from the cooler are kept very low. It will also be noted that the suction strokes of the dosing device pairs 12A and 12B overlap slightly, so that there is a continuous flow of yoghurt through the pipe 1. The motors driving the dosing devices 12A and 12B are programme-controlled as in EP-A- 287201.

In order further to promote maintenance of the structure/viscosity of the yoghurt from the cooler, it is advantageous to make the diameter of the closure member of each rotary valve 6A or 6B relatively large, so that the port cross-sections can be relatively large and the flow through the valve is smooth.

Arranging the dosing device 12A or 12B with its longitudinal axis perpendicular to the flow axis through its rotary valve 6A or 6B enables the valve ports to be as close as possible to the pumping chamber of the dosing device 12A or 12B and so mitigates stress on the yoghurt at that location. By making the suction stroke of each dosing device partially over two machine cycles and increasing the port cross-section, the product speed through the inlet port in the suction stroke can be 15% of that with a conventional apparatus. By performing the suction stroke partially over two machine cycles, the mass forces can be reduced by up to 90% compared with such conventional apparatus.

Owing to the low product velocity it should be possible to fill low viscosity products as well without needing to employ a balance tank on the machine.

The square filler nozzles 9 are preferably of two different characters; one used for low viscosity products and the other used for high viscosity products.

The suck-back device 7A or 7B can be integrated in the valve 6A or 6B instead of being located in the outlet duct 8A or 8B.

With the embodiment described with reference to the drawings it is possible to obtain low product flow velocity through to the dosing devices and still maintain high machine output and a good filling accuracy. Moreover, there can be direct feed from the cooler without any intervening balance tank. Furthermore, the forces on the dosing device diaphragm and thus the suction forces on the product can be approximately 90% lower than with a known dosing device. Moreover, the pressure loss, i.e. friction in the supply ducting, can be reduced by up to approximately 70%.

Claims

C-L JϋS

1. Apparatus for dosing fluid product, comprising supply means (1,5) for supplying said fluid product, a plurality of dosing devices (12) each arranged to perform, alternately, an intake action to take in said fluid product and a delivery action to deliver said fluid product, indexing means (13) arranged to index past said dosing devices (12) whereby said dosing devices (12) can deliver doses of said fluid product to said indexing means (14) , and control means for controlling said dosing devices (12) such that said dosing devices (12) operate out of phase in relation to each other, characterised in that said control means so controls said dosing devices (12) that the duration of each intake action of each dosing device (12) is longer than the duration of each indexing cycle of said indexing means (13) .

2. Apparatus according to claim 1, wherein said control means so controls said dosing devices (12) that the duration of each delivery action of each dosing device (12) is longer than the duration of each movement period of said indexing means and that the sum of said duration of each delivery action and said duration of each movement period is substantially equal to said duration of each indexing cycle.

3. Apparatus according to claim 1 or 2, wherein said dosing devices (12) are arranged in groups (12A, 12B) which are operated out of phase with each other.

4. Apparatus according to claim 1 or 2, wherein said control means is able to control said dosing devices (12) such that said dosing devices (12) are operable not only out of phase with each other, but, alternatively, in phase with each other.

5. Apparatus according to any preceding claim, wherein said supply means (1,5) comprises a supply conduit (1) common to said dosing devices (12) and inlet ducts (5) to the respective dosing devices (12) , said apparatus further comprising a plurality of rotary valves (6) in communication with the respective dosing devices (12) and through which said fluid product flows into and out of the respective dosing devices (12) .

6. Apparatus according to claim 5, wherein said rotary valves (6) are the only valves between said supply conduit

(1) and respective outlets of said dosing devices (12) .

7. Apparatus according to claim 5 or 6, wherein each dosing device (12) has a longitudinal axis which is substantially perpendicular to an axis of flow through the rotary valve (6) in communication therewith.

8. A method of dosing fluid product, comprising supplying fluid product to a plurality of dosing devices (12) during respective intake actions of said dosing devices (12) , indexing receptacles (14) past said dosing devices (12), dosing the fluid product from said dosing devices (12) into said receptacles (14) during respective delivery actions of said dosing devices (12) , and controlling said dosing so that said dosing devices (12) operate out of phase in relation to each other, characterised in that the duration of each intake action of each dosing device (12) is longer than the duration of each indexing cycle of said receptacles (14) .

9. A method according to claim 8, wherein the duration of each delivery action of each dosing device (12) is longer than the duration of each movement period of the indexing receptacles (14) , and the sum of said duration of each delivery action and said duration of each movement period is substantially equal to said duration of each indexing cycle.

10. A method according to claim 8 or 9, wherein groups (12A, 12B) of said dosing devices (12) are operated out of phase with each other.

11. A method according to claim 8 or 9, and subsequently operating said dosing devices (12) in phase with each other.