GB2425523A

GB2425523A - Depositing doses of a fluid

Info

Publication number: GB2425523A
Application number: GB0508625A
Authority: GB
Inventors: Senake Atureliya
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-28
Filing date: 2005-04-28
Publication date: 2006-11-01
Also published as: GB0508625D0

Abstract

Apparatus to dose out particular quantities of fluid comprises a peristaltic pump arrangement wherein a flexible pipe (1) is deformed by rollers (3, 4) to trap doses of the fluid (15) which move along the pipe due to the rotary motion of the apparatus and are dispensed at a receiving end (11). The size of the fluid dose maybe varied by changing the distance between the closed off sections of pipe (6). In another embodiment the pipe is closed off in two places by two rollers so as to trap a dose of fluid and the rollers are moved linearly past the end of the pipe to meter out the fluid. The size of the dose depends upon the distance between the two rollers which move in a linear reciprocal motion.

Description

METHOD AND APPARATUS FOR THE DEPOSITING OF VOLUMETRIC QUANTITIES OF

LIQUIDS WITH VARYING AMOUNTS OF SUSPENDED SOLIDS

The present invention relates to an improved means for the dispensing of predetermined target volumes of liquids that may contain suspended solids.

There are currently many requirements to fill packaging in the food and pharmaceutical industries with fixed volumes of liquid products achieving as good repeatability as possible. Some of these liquid products may also contain some suspended solids.

Many packaging operations now require numerous short production runs to satisfy modern consumer demands. Machinery involved in the production of these products must be able to be fleable to allow frequent product changes. Two important requirements are therefore the speed of cleaning to mimimise production downtime and minimization of product wastage at the end of a run.

Positive displacement depositors using a piston within a cylindrical chamber are commonly used for this purpose as they offer good volumetric accuracy with high speed, however, the piston depositor has major drawbacks. They are relatively complicated and must be stripped down for cleaning. Secondly, the depositing nozzle used to have a horizontal cut off at its mouth to stop drips and maamize accuracy, however recent safety legislation has banned this element of the design due to the trapping hazard. An older vertical plunger design has had to be reimplemented which gives lower dosing accuracy and can allow dripping onto the sealing edge of packaging media.

The peristaltic pumping princIe used in many industrial pumps is generally not used for the depositing of sauces for reasons relating to speed and dosing accuracy. Standard peristaltic pumps trap envelopes of liquid in portions of the tubing running through the pump head. As the pump head rotates successive volumes of liquid trapped within the envelopes is fed through the pump gMng a pulsed but consistent flow rate. If a peristaltic pump is used for dispensing a set volume of liquid as opposed to maintaining a thed flow rate, then as it is not possble to control the percentage of part of an envelope that is pumped into the filling nozzle, in order to ensure good repeatability it is necessary for the required dose to equal the volume of an exact fixad number of these envelopes. Alternatively, if the tubing is of a relatively small bore with many envelopes making up a single dose then the dosing accuracy would be limited to the volume of a single smaller envelope. As well as being more time consuming to clean, smaller tubing would restrict the dosing speed and be more prone to blockages where the liquid contained suspended solids.

According to one aspect of the present invention there is provided a method of dispensing liquid from a container holding a quantity of the liquid at a supply station into packaging at a receMng station, the method comprising a variation on conventional peristaltic pump that facilitates adjustment of the size of the envelopes created by pinching the tube and that provides an adjustable time interval between the delivery of the liquid in the envelopes. The tube is constructed so that whilst it can be deformed, the circumference of its bore does not noticeably change. The container does not form part of the invention. There is a controllable pressure forcing the liquid along the tube from the supply station to the receMng station.

This method could much increase the dosing accuracy of the peristaltic pumping mechanism and ensure that on and off periods required to meet the constraints of a packaging line are met.

The product to be dispensed may be liquid, a combination of solid and liquid or a combination of liquid and gas.

In embodiment of the invention there would be a length of fleable tubing lying on a substrate.

One end of the tube at the supply station would rest below the level of the liquid in the supply container. The other end of the tube would be positioned to feed into the packaging at the receiving station. Two rollers are incorporated into a mechanism that allows the distance between their axis to be adjusted. The mechanism would allow the rollers to be pressed down onto the tube to clamp it down onto the substrate and blocking it at two points along its length such that a void of fixed volume was created inside the tube between the two points at which it was blocked off. The mechanism upon which the rollers were mounted would allow them to travel along the length of the tubing moving the void along the tube. The path along which the rollers travelled would extend past the ends of the tube supporting substrate at both the supply station and receiving stations. On the forward pumping stroke, this would allow the leading roller to clamp the tube and draw the void forwards towards the receMng station whilst leaving the end of the tube supplied by the feed container open to allow liquid to be sucked into the tube to fill the void. When the trailing roller reached the end of the substrate it would clamp the tube and fix the size of the dose trapped in the void between the rollers. When the leading roller reached the end of the supporting substrate the front of the void would be opened dispensing and the trailing roller would continue rolling to dispense the contents of the void out into the packaging. The trailing roller would stop at the end of the substrate to prevent the liquid in the void behind it from reaching the receiving station. The rollers would then reverse back along the tube towards the supply station with the trapped void between the rollers being empty.

Advantageously whilst reversing towards the supply station the rollers would push liquid drawn up into the tube behind the trailing roller back into the supply container to agitate any solids mixed into the liquid which had settled at the bottom of the supply container which could contribute towards blocking of the tube Advantageously the tubing would be fixed relative to the substrate at one or more points to prevent it from moving when the rollers moved down its length.

In a preferred embodiment of this invention the rollers would be grouped together in pairs with a belt running between them. The belt could be constructed from one or more pieces of material.

The belt would be supported in the gap between the rollers such that it compressed the tube between its supporting rollers to the same degree as the rollers themselves. This arrangement would allow several doses of the liquid to be trapped in the multiple voids created in the tubing between the sets of rollers. Within a set, when the lead roller, belt and trailing roller were compressing the tube no liquid would be trapped in the compressed section. This would the rollers to move along the tube in a continuous motion with discrete doses of liquid being deposited at the receiving station interspaced by periods of zero low to allow removal of a filled package and substitution of an empty one. The time interval between deposits would be determined by the distance between the grouped rollers and their speed of travel along the tube.

In a preferred arrangement of this invention the sets of rollers would move in a cyclical motion to eliminate waiting time for the rollers to return from the receiving station to the supply station.

In a preferred arrangement of the invention there would be a multiplicity of tubes lying substantially parallel to each other to allow liquid to be fed into a multiplicity of containers.

In a preferred arrangement of the invention there would be a multiplicity of tubes lying substantially parallel to each other to allow liquid to a number of the tubes to feed individual containers at a higher rate than would be possible through a single tube.

Advantageously in the arrangement where a number of tubes were feeding into a single container the diameter of the tubes would differ in size to allow greater control over the accuracy of the deposit by combining the increased accuracy of the smaller bore tubes with the larger depositing capability of the larger tubes.

The present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figures 1 illustrates a cross sectional view from one side of the invention with a container of liquid, tube, rollers and supporting substrate being part of a liquid dispensing system in accordance with the invention, Figures 2 illustrates a cross sectional view from one side of the invention with a container of liquid, tube, sets of rollers connected by belts and a supporting substrate being part of a liquid dispensing system in accordance with the invention, Figure 3 illustrates a view from above of the invention comprising a multiplicity of dosing tubes feeding into a multiplicity of packaging trays.

All the drawings illustrate systems for dispensing liquids or liquids with particulate solids from a container to a conveyor carrying packaging containers or alternatively carrying semi-prepared products such as tart cases requiring the application of fillings.

Referring to the drawings, Figures 1 illustrates a pressunsed container I with a lid 11 that contains a product comprising liquid and particulate solids. A compressible tube 2 extends from the container where one of its ends in submerged in the contents of the container at the supply station along a substrate 3 to a receMng station under which packaging trays 4 are passing on a conveyor (not shown). The tube is compressed at two points by a leading roller 5 and a trailing roller 6 such that a void 7 is formed within the bore of the tube. The rollers are mounted on a carriage 8 that allows the distance between the axis of the rollers to be altered. The carriage 8 is able to slide in a direction along the length of the tube on a track 9.

Before the apparatus can be used, it needs to be primed. The steps required to achieve this are as follows: 1. The container I is filled with liquid and the lid 11 is closed.

2. The track 9 and carriage 8 are moved away from the substrate 3 such that the tube 2 is no longer clamped by either of the rollers 5 and 6 3. The pressure of the gas in the container above the liquid is then increased so that the liquid flows along the tube.

4. When the liquid has reached the end of the tube at the receiving station, the valve 10 is closed.

5. The track 9 is moved closer to the substrate 3 such that the rollers 5 and 6 clamp the tube 2 in the position shown.

The sequence of motion of the system during the depositing operation is as follows: 6. The carriage 8 moves down the track 9 towards the packaging moving the roller 5 past the lower end of the substrate 3 such that the end of the tube is no longer closed. As the trailing roller 6 moves along the tube 2 the liquid trapped in the void 7 is ejected out of the open end of the tube into the packaging. The carriage stops moving when the trailing roller 6 is at the lower end of the substrate.

7. Valve 10 closes the tube.

8. The packaging container 4 that received the liquid is removed and replaced with an another packaging container that requires a deposit of liquid.

9. The track 9 is then moved away from the substrate 3 so that the tube 2 is no longer clamped by either of the rollers 5 and 6 The carriage 8 is then moved upwards along the track so that the leading roller 5 is in line with the lower end of the substrate 3.

11. The track 9 is then moved towards the substrate 3 so that the rollers 5 and 6 close the tube at two points to form the void 7.

12. The sequence of operations as per steps 6 to 11 above are repeated to deposit into successive packaging containers.

Figure 2 illustrates a preferred arrangement of the invention in lkiuid 2 from a container (not shown) is contained in a tube 1. A leading roller 3 and a trailing roller 5 are mounted on a frame such that the distance between their ads can be adjusted using a mechanism (not shown). A belt 5 runs around the rollers and also an idler roller 9. The idler roller is fixed to the frame upon which the rollers are mounted by a tensioning mechanism 13 such that the belt is kept taught between the three rollers The adjustable length runner 6 supports the length of belt running between the rollers on the opposite side from that in contact with the tube. A number of these roller sub assemblies are fixed to a central shaft 8 by supports 7. The tube is fixed into a housing against a substrate 14. A packaging container 11 is located at the receiving station under the end of the tube.

The sequence of motion of the system during the depositing operation is as follows: 1. The rollers 3 and 4 move around the shaft 8 in an rotary anticlockwise motion.

2 A leading roller 3 seals the tube I by squeezing it against the substrate 14 as it moves around the aas 8.

3. As the leading roller 3 moves further, the length of tube 2 behind the leading roller 3 is compressed by the belt 5 supported by the runner 6 and the substrate 14 such that the bore of the tube is reduced to zero between the leading roller 3 and trailing roller 4 mounted on the same frame 10.

4. When the trailing roller 4 has passed the leading edge of the substrate 14 the elasticity in the tube assists it in recovering its originl shape and its bore is opened.

5. As the rollers move further around the axis of the shaft 8, liquid 2 is drawn into bore of the tube.

6. The leading roller 3 on the adjacent frame compresses the tube 2 against the substrate 14 creating a void 15 full of liquid.

7. As the rollers rotate around the shaft 8 the void 15 full of liquid 2 is moved along the tube 1 towards the receiving station.

8. As the trailing rollers in each frame move past the end of the substrate 14 they allow the tube to recover its shape allowing the liquid from each void 15 to be released into the packaging container 11.

9. The liquid 2 is ejected from the void 15 as the leading roller 3 on the adjacent frame moved the void along the tube 1 towards the receiving station. When the leading roller reaches the end of the substrate 14 the flow is cut off allowing the packaging container 11 that contains the deposit to be replaced by another packaging container 11 that requires a deposit.

10. The steps 2 to 9 are repeated to deposit into multiple packaging containers 11 presented in turn at the receiving station.

11. To increase the volume of the deposit the leading roller 3 and trailing roller 4 on each frame 10 can be moved closer together to reduce the length of tube I compressed beneath the rollers and belt 5 increasing the length of the trapped voids 15 of liquid.

When the distance between the leading roller 3 and trailing roller4 on each frame is varied, the idler roller 9 will take up any slack in the belt 5. The runners 6 will incorporate a sliding interleaved sliding arrangement (not shown) to allow their length to be changed support the elongated or shortened belt 5.

Claims

METHOD AND APPARATUS FOR THE DEPOSITING OF VOLUMETRIC QUANTITIES OF

LIQUIDS WITH VARYING AMOUNTS OF SUSPENDED SOLIDS

1. A method used to dose out material comprising of liquid that may contain a quantity of suspended solids, the mechanism includes a flexible section of pipe and means for moving a multiplicity of doses along the pipe by trapping them between deformed sections of the pipe.

2. A method according to claim I where each dose is contained within a section of flexible pipe by sufficiently delbrming the pipe at two clamping points to reduce the bore of the pipe to zero cross sectional area so that the material located between the two points cannot flow past these points. The means used to deform the pipe at these clamping points can be moved along the pipe to allow the trapped dose to be pumped along the pipe from a supply pint to a receiving point 3. A method according to claim 2 that allows the distance between the two clamping points to be altered to change the volume of the sections of pipe holding the dose.

4. A method accoiding to claims 2 or3 where the means of deforming the pipe at the clamping points keeps the bore of the pipe dosed for a predetermined adjustable length between the sections holding the doses of material.

5. A method according to claIms 3 or 4 where the mechanism of deforming the pipe move along a reciprocal path that allows them return to deform the pipe near the supply point after they have moved past the end of the pipe at the receiving point.

8. A method according to claim 5 whereby the mean of deforming the pipe move at a constant linear speed along the reciprocal path to facilitate the repetitive dosing of the material at preset intervals at the receiving point 7. A method according to claim S where the mechanism of deforming the pipe move in a circular path and the ratio between the length of the sections of pipe containing each dose and those not containing a dose can be varied to allow the dosing volume and delay between doses to be altered by changing the speed at which the clamping points move along the pipe and this ratio.

8. A method according to claims 3 or 4 where the means of deforming the pipe moves in a reciprocating motion along a linear path such that the clamping point nearest to the receiving end of the pipe moves to allow the pipe to open up at the receiving end at a predetermined time to allow the material to flow out of the pipe and reclamp it at another predetermined time to stop the material flowing out of the pipe. The second clamping point moves along the pipe to eject the dose out of the pipe at the receiving end.

9. A method according to claim 5 or claim 7 or claim 8 where an additional valve is located at the receiving point to enable the dosing mechanism to be located further away from the dosing mechanism than in claim 5 or claim 7 or claim 8.