WO2009130250A1

WO2009130250A1 - A linear peristaltic dispensing apparatus and method for use of the apparatus

Info

Publication number: WO2009130250A1
Application number: PCT/EP2009/054833
Authority: WO
Inventors: Jesper Bjørn HANSEN
Original assignee: Trepko A/S
Priority date: 2008-04-22
Filing date: 2009-04-22
Publication date: 2009-10-29

Abstract

A linear peristaltic dispensing apparatus ( 1; 1 ' ) comprising a reservoir (2) serves for dispensing a substance. The reservoir (2) has a reservoir inlet (11) and an opposing reservoir outlet (9), a substance tube (7) defining a dispensing axis (A), which substance tube (7) has a first end (8) in communication with the reservoir outlet (9), and an opposing discharge end (10) for discharge of an amount of substance, and peristaltic means for dispensing the amount of substance out through the discharge end (10) of the substance tube (7). The peristaltic means comprises a first roller (6a), a contrarotating second roller (6b) facing the first roller (6a), and actuator means (5) for moving the rollers (6a, 6b) in relation to the substance tube (7) suspended between the rollers (6a, 6b). The apparatus is particular suited for dispensing and metering accurate doses of viscous or fully liquid substances.

Description

A linear peristaltic dispensing apparatus and method for use of the apparatus

The present invention relates to a linear peristaltic dispensing apparatus comprising a reservoir for a substance, in particular a viscous substance, which reservoir has a reservoir inlet and an opposing reservoir outlet, a substance tube defining a dispensing axis, which substance tube has a first end in communication with the reservoir outlet, and an opposing discharge end for discharge of an amount of substance, and peristaltic means for dispensing the amount of substance out through the discharge end of the substance tube.

In particular the present invention relates to a linear peristaltic dispensing apparatus for dispensing substances having a high viscosity.

The present invention also relates to a method of dispensing by means of the linear peristaltic dispensing apparatus.

Within the scope of the present invention the term, "peristaltic" is to be understood as the action in which fluid is forced along by mechanically depression and contraction of a flexible tube, and the term "dispense" means deal out in portions or doses. A discussion of rotary and linear peristaltic pumps is found in International patent application no. WO98/31935.

The term "viscosity" is used to describe the property of a fluids resistance to flow. "High viscosity" means high resistance to flow and "low viscosity" means low resistance to flow.

Dispensing accurate doses or portions of fluids puts great demand on the dispensing apparatus. Liquids have low viscosities and flow fast through a tube, putting great demand in the opening and closing of the dispensing operation. Accurate doses of viscous substances are particular difficult to dispense. The force required for the dispensing operation is substantial, and the dispensing apparatus are often difficult and laborious to clean after use. Examples of viscous substances include mayonnaise, butter, margarine, dough, minced meat, cosmetic cream and any kind of creamy and pastelike substances .

From BE1011250 is known a dosage pump for liquids, semi-liquid materials and pastes. The pump includes a flexible hose that is connected to a reservoir for the liquids, semi-liquid materials and pastes at one end. The hose is subjected to a series of stampers that squeeze the hose in sequence so that a fluid wave motion is generated by the stampers, moving a pre-defined amount of material or paste along the flexible hose and thereby delivering it from the pump outlet. This known dosage pump illustrates substantially the principle of a linear peristaltic pump. Linear peristaltic pumps are unable to pump at high flow rates and accurate doses are difficult to dispense.

From EP0609513 is known a packaging machine, which has both a feed device and a metering device. The feed device includes two vane pumps having spaced apart rollers situated near the floor of a product receiving housing symmetrically to an outlet channel of the housing. The rollers are rotatably driven in opposite directions. The feed unit has a control valve located beneath an input channel for the paste product and cylinder- piston feeders on both sides. The outlet channel is linked to a metering device by an inlet channel.

US2006/0228240 Al discloses a method and an apparatus for dispensing products of various viscosities. The apparatus includes a non-invasive linear peristaltic pump having a linear traction plate, a depressor which is pressed against a stationary traction plate using a driver means. The depressor compresses a product tube between the linear portion and the depressor such that an inner passage of the product tube is substantially sealed. The driver draws the depressor downwards along the linear portion of the traction plate, such that the product tube is depressed and product is dispensed. Due to the fact that the traction plate is stationary, compression force are applied and controllable from only one side perpendicular to the product tube which may result in that the discharge end of the product tube deflects and dispensed product splashes at the end of the dispensing stroke. Furthermore, the product tube must be able to resist considerable frictional force when the depressor moves along the length of the product tube in order not to induce damage to the product tube.

U.S. Patent Application No. 2004/0022656 discloses a peristaltic apparatus for depositing viscous liquids. In one embodiment the apparatus comprises a flexible tubing and a pair of rollers for compressing the tubing. Each roller follows a predefined oval travel path. The rollers' arcuate travel path is controlled by an attached dogleg member, which is actuated about two pivot points by a compression cylinder. Accordingly, it is not possible to vary the rollers' travel path substantially as would be needed when depositing liquids of considerably different viscosities. Also, the travel path is obligatorily arcuate, which makes it difficult to precisely control the degree of compression of the tubing.

The known linear dispensing apparatuses have several limitations and disadvantages which the present invention aims to overcome.

It is a first aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which is a versatile alternative to prior art apparatuses. It is a second aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which can dispense both high volume and low volume doses according to need in a reliable, repeatable manner and with a faster dosing rate than known apparatuses.

It is a third aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which is easy to make ready for operation and to operate, in particular is easy to clean.

It is a fourth aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which is particularly suited for different substances having a wide range of respective viscosities.

It is a fifth aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which is particularly suited for substances containing large particles - even volatile particles.

It is a sixth aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph which operates in continuous dispensing mode with the lowest possible risk of contamination.

It is a seventh aspect according to the present invention to provide a dispensing apparatus of the kind mentioned in the opening paragraph allowing the precise control of the degree of compression of the substance tube.

It is a eighth aspect according to the present invention to provide a method for dispensing substances by means of the dispensing apparatus. The novel and unique whereby this is achieved according to the present invention is the fact that the peristaltic means comprises a first roller, a contra rotating second roller facing the first roller, and actuator means for moving the rollers in relation to the substance tube suspended between the rollers .

Conventional peristaltic pumps with rotating rollers uses successive spaced apart compressive rollers to occlude a flexible tube which is supported by a circular backstop upon moving in a circumferential, circular arc over the tube and depressing the tube against the backstop. Such rotary peristaltic pumps are only capable of pumping low viscosity liquids at very low discharge pressures and at very modest flow rates and the tube life is short. Furthermore, such pumps cannot increase or adjust the total compression force acting upon the tube in order to control dispensing rate, amount of substance to be dispensed and to dispense viscous substances.

Contrary to the conventional pumps based on rollers in a peristaltic principle the dispensing apparatus according to the present invention does not use a fixed backstop. Instead a substance tube is suspended between two rotating rollers, which during rotation are moved by means of the actuator means, to squeeze a substance out of the substance tube suspended between the rollers. By using opposing rotating rollers the frictional force applied to the substance tube can be substantially reduced and prolonged lifetime of the substance tube is obtained. Furthermore, the volume, weight or amount of dispensed substance is easy to control by simply adjusting e.g. the length of stroke.

In the preferred embodiments according to the present invention the actuator means is adapted to repeat a cycle of dispensing stroke steps to dispense a plurality of identical doses, one after another, for example into a corresponding number of receptacles on a moving conveyer belt below the discharge end of a suspended substance tube. The apparatus according to the present invention is also suitable for use in a completely continuous or semi-continues product line, including sealing and packing equipment using for example plastic- and paper pouches, tins, buckets, plastic containers as receptacle, or in a large-scale catering establishment using a plate as receptacle for the dispensed substance.

The dispensing stroke steps may in this preferred embodiment take place along the length of the suspended substance tube between an upper first position of the rollers and a lower second position of the rollers to squeeze out the predetermined or preset amount of substance in dependency of the stroke length, i.e. the distance the rollers travel along the suspended substance tube. When the apparatus is configured as a horisontal dispensing apparatus, the terms "upper" and "upper" means proximal, i.e. closest to the reservoir, and "lower" means distal, i.e. closest to the discharge end of the substance tube.

In a first dispensing stroke step the rollers move towards each other from a starting position to an upper first position to reduce the gap between the rollers and constrict the substance tube a predetermined degree. Hence, the gap may be partly or fully eliminated by approaching and adjoining the rollers. If preferred the only material keeping the rollers out of direct contact may be the material of the wall of the substance tube. Hence, in the first dispensing stroke step a predetermined gap size is defined and selected for a certain cycle based for example on parameters such as the consistence, viscosity, amount of substance to be dispensed and dispensing rate. The size of the gap further influences the fine-side pressure by means of which the next dose or portion of substance is drawn along into the substance tube during a subsequent second dispensing stroke step. A small gap provides a higher fine-side pressure than a big gap. In the second, translatory dispensing stroke step the contrarotating rollers may move to the lower second position of the rollers, preferably the size of the gap is kept constant. As a result of the second dispensing stroke step a predetermined dose is dispensed. The dose may be received in a suitable receptacle below the discharge end of the substance tube. In a third dispensing stroke step the rollers may move apart to regain a sufficient gap between the rollers to allow the rollers to in a fourth dispensing stroke step return to their starting position. During this return stroke the stroke length of the substance tube is fully refilled with substance, partly due to gravity and partly due to the negative pressure resulting from the second dispensing stroke step, and the dispensing cycle can be repeated. The rollers may be forcibly contrarotated, e.g. by a separate motor, or the contrarotation may be induced by means of the actuations means during the rollers downwards motion from the first position towards and to the second position. In both cases the direction of rotation of both rollers is towards the substance tube. This dispensing cycle has the ability to provide sustained pumping and precision metering of in particular viscous substances, for example mayonnaise or paste.

According to another embodiment of the dispensing apparatus the actuator means is adapted to repeat a cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers, which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap between the rollers and squeeze the substance tube, a second dispensing stroke step, in which the contrarotating rollers move to the upper first position of the rollers, a third dispensing stroke step, in which the rollers move to the lower second position of the rollers, a fourth dispensing stroke step, in which the rollers move apart to regain the gap between the rollers, and a fifth dispensing stroke step, in which the rollers return to their starting position. The rollers' intermediate third position will typically be located at a short distance, for example one centimetre, below the upper first position, if the substance tube is arranged vertically. This embodiment is advantageous when dispensing liquids of low or medium viscosity such as water, juice or yoghurt. In embodiments where the dispensing apparatus comprises one or more valves for opening and closing the flow passage through the substance tube it is seen that low- viscosity liquids splash from the tube's discharge end with excess pressure when the valve is opened while the tube is compressed. The excess pressure will build up when the rollers move towards each other in the first dispensing stroke step for squeezing the tube while the valve is still closed. With the second dispensing stroke step of the present embodiment, wherein the rollers move from their intermediate third position to their upper first position while squeezing the tube, this excess pressure can be relieved while, or shortly before, the valve is opened for discharge. This has been found to efficiently prevent splashing and reduce substance loss when working with liquids of low or medium viscosity. The rollers' travel path between the intermediate third position, the upper first position and the lower second position, respectively, is preferably linear.

According to yet another embodiment of the dispensing apparatus the actuator means is adapted to repeat a cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap between the rollers and squeeze the substance tube, a second dispensing stroke step, in which the contrarotating rollers move to the upper first position of the rollers, a third dispensing stroke step, in which the rollers move to the lower second position of the rollers, a fourth dispensing stroke step, in which the rollers move to an intermediate fourth position between the upper first position and the lower second position, a fifth dispensing stroke step, in which the rollers move apart to regain the gap between the rollers, and a sixth dispensing stroke step, in which the rollers return to their starting position. If the substance tube is arranged vertically, the intermediate fourth position of the rollers lies below the upper first position and the intermediate third position, respectively, and shortly above, for example one centimetre, the lower second position. By moving the rollers from the lower second position to the intermediate third position while the rollers squeeze the substance tube it is advantageously achieved that a small amount of substance is drawn back into the tube in a direction opposite the discharge direction. This may lead to a dispensing process that is more hygienic and exhibits less substance loss, since substance remaining at the discharge opening after discharge has taken place is drawn back a short distance into the tube.

In an expedient embodiment of the dispensing apparatus the actuator means is adapted to repeat a cycle of dispensing stroke steps, wherein the rollers follow along a rectangular travel path at least during part of the cycle. Hereby, it is achieved that the dispensing stroke steps are more precise and result in a more precise dispensing process as opposed to systems employing an arcuate travel path of the rollers. With the latter the tube is compressed and distended more gradually both over time and over length, whereas a rectangular travel path ensures a more prompt and precise regulation of the discharge process in response to changes in the rollers' relative position. Accordingly, a rectangular travel path permits sharper compression profiles when, for example, the degree of tube compression is plotted versus time. With a rectangular travel path the dispensed substance volume relates to a more defined and confined tube-compression pattern, which is not only accurate and repeatable, but renders a precise dispensing more independent of variations in the substance's viscosity

A rectangular travel path is made possible by roller actuation means that permit free and independent movement of the rollers both in the vertical and in the horizontal direction. These may include a gear transmission for actuation of the vertical movement of the rollers parallel to the length of the substance tube. Independent pneumatic cylinders may be used for actuating horizontal movement of the rollers in a direction perpendicular to the longitudinal axis of the substance tube. Both for horizontal and vertical movement of the rollers any suitable actuation means may be used, including electrically or mechanically actuated pistons.

In order to keep the substance tube distended in particular during the last dispensing stroke step, in which the rollers return to their starting position, at least the part of the substance tube subjected to the cycle of dispensing strokes may be situated in a vacuum chamber. The vacuum chamber also serves for creating or increasing the fine-side pressure and for preventing collapse of the substance tube during repetitions of the dispensing cycle. A vacuum chamber is particular expedient if the substance tube has a very small wall thickness and/or is made from a very flexible material. A disposable substance tube may e.g. be cut from a continuous roll of thin tubing, e.g. polyethylene tubing of the kind acceptable for storing food. The cut piece can be mounted in closed fluid communication with the reservoir via the reservoir outlet using e.g. a manacle ring or other kinds of fasteners. No cleaning is required when the substance tube is disposable. For some low viscous substances and/or if high dispending rate is less important the vacuum chamber may be dispensed with.

It is preferred that the dispensing apparatus comprises at least one valve for opening and closing the flow passage through the substance tube during any appropriate stage of the dispensing cycle, but at least during the last step of the dispensing cycle. The valve advantageously serves for preventing substance, in particular low viscosity substances such as liquids, from unintentionally dropping or flowing immediately out of the discharge end of the substance tube when the rollers is spaced apart. The point of time at which the valve may open and close during a dispensing cycle may vary depending on e.g. substance, dispensing speed and metering precision. If for example a valve distal to the lower second position of the rollers is kept closed during at least a part of a dispensing stroke step a positive pressure may build up in the confined length of the section of the substance tube. The positive pressure increase expelling force out of the discharge end of the substance tube.

In a simple embodiment the at least one valve for opening and closing the flow passage through the substance tube is a pair of opposing clamps distal to the lower second position of the rollers. At the end of the dispensing stroke step in which the rollers move to the lower second position, the clamps confine the next dose above the closed clamps until the first dispensing stroke step starts the next dispensing cycle. The clamps advantageously keep the substance tube constricted when needed and provide for a predetermined dose to be dropped distal to the clamps.

Any of the actuator means and the at least one valve may be operated and controlled by any suitable means, e.g. a hydraulic motor or piston, a pneumatic motor or piston, or an electrical motor or combinations of these. To facilitate replacement of various substance tubes, especially a reusable substance tube, the first end of the substance tube may have a first fitting for coupling with a second fitting part on the reservoir. The fitting parts may e.g. be a union fitting. In this embodiment the substance tube may easily be unscrewed to be cleaned for use with a new substance. In addition, whether or not the substance tube is reusable or disposable, the reservoir may have a disposable lining for further reducing laborious and potential inefficient cleaning of the reservoir. Accordingly, the apparatus according to the present invention is very easy to keep clean. Furthermore considerable efforts, man-hours and costs for water and cleansing agent are saved and contamination risk minimal.

If at least the operation of the actuator means and/or the at least one valve is controlled by a computer program run on a computer, any parameter for operating the dispensing apparatus can be used to operate the apparatus in accordance with the characteristics of the product or substance to be dispensed, the product line parameters etc., such as pressure on the substance tube, substance flow rate, cycle frequency, viscosity, and conveyer belt speed. An interface may be used for entering the data for the parameters. An advanced computer programme may be particular designed for operating the apparatus. Such a computer programme may include a database storing modes of operation for different substances. By means of the interface the proper programme is activated following filling of the reservoir and mounting of an appropriate substance tube. However, a less advanced PLC (programmable logic controller) and PLC program can also be used.

The dispensing apparatus according to the present invention may be either a vertical or a horizontal linear dispensing apparatus. By "vertical" is to be understood that the dispensing stroke step cycle is repeated in a substantially vertical manner along a vertically suspended substance tube in relation to a support face for the apparatus, and by "horizontal" is to be understood that the dispensing stroke step cycle is repeated in a substantially horizontal manner along a horizontally suspended substance tube in relation to a support face for the apparatus .

As mentioned above the invention also relates to a dispensing method for dispensing a dose of substance. The method includes the steps of mounting a substance tube on a substance reservoir outlet of an apparatus according to the present invention and filling the reservoir. Subsequently the operational parameters of the apparatus according to the present invention are applied to the apparatus in order to dispense a plurality of doses or portions of substances.

In a preferred embodiment of the dispensing method the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers, which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to an upper first position to reduce the gap between the rollers and squeeze the substance tube a second dispensing stroke step, in which the contrarotating rollers move to the lower second position of the rollers, a third dispensing stroke step, in which the rollers move apart to regain the gap between the rollers, and a fourth dispensing stroke step, in which the rollers return to their starting position. This dispensing cycle has the ability to provide sustained pumping and precision metering of in particular viscous substances, for example mayonnaise or paste.

According to another embodiment of the dispensing method the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers, which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap between the rollers and squeeze the substance tube, a second dispensing stroke step, in which the contrarotating rollers move to the upper first position of the rollers, a third dispensing stroke step, in which the rollers move to the lower second position of the rollers, a fourth dispensing stroke step, in which the rollers move apart to regain the gap between the rollers and a fifth dispensing stroke step, in which the rollers return to their starting position. The rollers' intermediate third position will typically be located at a short distance, for example one centimetre, below the upper first position, if the substance tube is arranged vertically. This embodiment is advantageous when dispensing liquids of low or medium viscosity such as water, juice or yoghurt, as already explained above.

According to yet another embodiment of the dispensing method the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers, which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to the upper first position to reduce the gap between the rollers and squeeze the substance tube, a second dispensing stroke step, in which the contrarotating rollers move to the lower second position of the rollers, a third dispensing stroke step, in which the rollers move to an intermediate fourth position between the upper first position and the lower second position a fourth dispensing stroke step, in which the rollers move apart to regain the gap between the rollers, and a fifth dispensing stroke step, in which the rollers return to their starting position. If the substance tube is arranged vertically, the intermediate fourth position of the rollers lies below the upper first position and the intermediate third position, respectively, and shortly above, for example one centimetre, the lower second position. By moving the rollers from the lower second position to the intermediate third position while the rollers squeeze the substance tube it is advantageously achieved that a small amount of substance is drawn back into the tube in a direction opposite the discharge direction, as already explained above.

According to yet another embodiment of the dispensing method the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length of the substance tube between an upper first position of the rollers and a lower second position of the rollers, which cycle comprises a first dispensing stroke step, in which the rollers move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap between the rollers and squeeze the substance tube, a second dispensing stroke step, in which the contrarotating rollers move to the upper first position of the rollers, a third dispensing stroke step, in which the rollers move to the lower second position of the rollers, a fourth dispensing stroke step, in which the rollers move to an intermediate fourth position between the upper first position and the lower second position, a fifth dispensing stroke step, in which the rollers move apart to regain the gap between the rollers, and a sixth dispensing stroke step, in which the rollers return to their starting position.

In a preferred embodiment of the dispensing method the rollers follow along a rectangular travel path at least during part of the cycle. Hereby, it is achieved that the dispensing stroke steps are more precise and result in a more precise dispensing process as opposed to systems employing an arcuate travel path of the rollers, as already explained above.

From the foregoing description of different cycles of dispensing stroke steps it should have become clear that the respective first, second, and following dispensing stroke steps of a given cycle may not necessarily correspond to the respective first, second and/or following dispensing stroke steps of another cycle according to another embodiment of the invention. In other words, the technical teaching related to, for example, the term "first dispensing stroke step" may differ between different embodiments of the present invention.

The invention will be explained in greater detail below describing further advantageous properties and examples of embodiments with reference to the drawings in which,

Fig. 1 shows, seen in perspective, a first embodiment of a vertical linear peristaltic dispensing apparatus according to the present invention in a first position of the rollers,

Fig. 2 shows in perspective and in enlarged scale the vacuum chamber and the actuator means,

Fig. 3 shows, seen in perspective, the first embodiment shown in fig. 1 in a first position of the rollers and at the end of a first dispensing stroke step,

Fig. 4 shows, seen in perspective, the first embodiment shown in fig. 1 in a second position of the rollers and at the end of a second dispensing stroke step, Fig. 5 shows, seen in perspective, the first embodiment shown in fig. 1 in a second position of the rollers and at the end of a third dispensing stroke step,

Fig. 6 shows, seen in perspective a reservoir and a substance tube provided with a fitting part,

Fig. 7 shows, seen in perspective, a second embodiment for a linear dispensing apparatus according to the present invention in a second position of the rollers and at the end of a second dispensing stroke step,

Fig. 8 shows schematically examples of dosing profiles achievable using the linear peristaltic dispensing apparatus according to the present invention,

Fig. 9 is a schematic flow diagram showing the travel paths of the first and second roller, respectively, during one type of cycle of dispensing stroke steps,

Fig. 10 is a schematic flow diagram showing the travel paths of the first and second roller, respectively, during another type of cycle of dispensing stroke steps,

Fig. 11 is a schematic flow diagram showing the travel paths of the first and second roller, respectively, during yet another type of cycle of dispensing stroke steps,

Fig. 12 is a schematic flow diagram showing the travel paths of the first and second roller, respectively, during yet another type of cycle of dispensing stroke steps, and

Fig. 13 shows schematically another set of examples of dosing profiles achievable using the linear peristaltic dispensing apparatus according to the present invention. In the embodiments shown in the figures the actuator means and the rollers are visible inside a vacuum chamber to elucidate the operating principle and promote understanding of the peristaltic movement. It is however to be understood that the presence of a vacuum chamber is optional and depend on the substance to be dispensed. The vacuum chamber can be a sealed unit, optionally having a see-through wall. Furthermore, the valve is illustrated as two opposing cylinders, which may be operated by any suitable means, mechanical, air driven etc, or have any appropriate design, including pivoting jaws. Furthermore, the feed reservoir can be of any design and the communication between the feed reservoir and the substance tube may be obtained by any suitable means. The size of the gap between the rollers is shown for illustrative purposes and the size is selected considering the characteristics of the substance and operation of the apparatus. Although the apparatus is shown as a vertical dispensing apparatus it is to be understood that the dispensing apparatus according to the present invention also can be arranged horizontally, using a cycle of substantially horizontal dispensing stroke steps.

Fig. 1 shows a first embodiment of a vertical linear peristaltic dispensing apparatus 1 according to the present invention .

The apparatus 1 comprises a reservoir 2 and a dispensing unit 3. The dispensing unit 3 includes a vacuum chamber 4 inside which an actuator means 5 for operating a set of opposing contrarotation rollers 6a, 6b along a length L of a substance tube 7. The substance tube 7 has a first end 8 in communication with the reservoir outlet 9, and an opposing discharge end 10 for discharge of an amount of substance (not shown) . Opposite the reservoir outlet 9 the reservoir 2 has a reservoir inlet 11 for feeding a substance to be dispensed. The vacuum chamber 4 is illustrated as being substantially cubic, but any appropriate shape can be implemented. Vacuum is created through the chamber outlet 12 by applying suction through the hose 13.

The actuator means 5 is seen more clearly in fig. 2. The actuator means 5 includes a gear transmission 113 for actuation of the vertical movement of the rollers 6a, 6b along the length L of the substance tube 7, that is in the direction towards the discharge end 10 of the substance tube 7, and pneumatic cylinders 19a, 19b for actuating horizontal movement of the rollers 6a, 6b, that is in a direction perpendicular to the axis A of the substance tube 7. Although pneumatic cylinders are described the means for actuating horizontal movement of the rollers can be of any suitable kind, including electrically or mechanically actuated pistons.

The gear transmission 113 is a rack 14 and pinion 15, which by means of a supporting frame 16 is connected to roller holders 17a, 17b for suspending the rollers 6a, 6b. The pinion 15 is a toothed wheel 15 and the rack 14 is a toothed rack 14. The teeth of the pinion 15 engages the teeth on the rack 14 to convert rotational motion into vertical linear motion of the rollers 6a, 6b along the length L of the substance tube 7. As a result, the rotational motion applied to the pinion 15 will cause the supporting frame 16 to travel along the rack 14 to cause the rollers 6a, 6b to travel from the upper first position shown in fig. 1 and to the lower second position shown in fig. 3 and 4.

The roller holders 17a, 17b may have any appropriate shape allowing the rollers 6a, 6b to rotate when at least translatory displaced along the length of then substance tube.

In the enlarged scale view of fig. 2 the substance tube and reservoir 2 is left out so that the structure of the actuator means 5, in particular the pinion 15 of the gear transmission

113 and the suspension of the rollers 6a, 6b, can be seen better. The rollers 6a, 6b are rotationally suspended in U- brackets 18a, 18b, through which the pneumatic cylinders 19a, 19b act to drive the rollers 6a, 6b towards and away from each other to achieve sizing of the gap G between the rollers. Power air for the pneumatic cylinders is supplied through air hoses 20a, 20b which are hermetical airtight arranged through a wall of the vacuum chamber 4. The gear transmission may be driven by any suitable means, such as e.g. a servo motor, as well as other means such as pistons may be used instead of the gear transmission for movement of the rollers in the inventive manner described above.

A valve 21 arranged at the discharge end 10 of the substance tube 7 serves for preventing unintentionally discharge of substance during the dispensing cycle. In a preferred embodiment the valve consists of two cooperating pivoting jaws arranged to shut off discharge of substance whenever appropriate during the dispensing cycle. Since the rollers 6a, 6b are spaced apart the substance can freely flow down towards the valve 21, which accordingly is closed to prevent discharge during performing the first dispensing step as shown in fig. 3.

Fig. 3 shows the rollers 6a, 6b in the upper first position and at the end of the first dispensing stroke step, where the rollers 6a, 6b have been driven towards each other by means of the pneumatic cylinders 19a, 19b to reduce the gap G. The valve

21 is still closed and the predetermined amount or dose of substance is entrapped between the rollers 6a, 6b, and the valve 21 is subjected to a slight elevation of pressure due to reduction of the volume V of the confined length of the substance tube 7.

As seen in Fig. 4, subsequently the rollers 6a, 6b move in the second dispensing stroke step towards the discharge end 10 in the direction B towards the valve 21. The valve 21 may be kept closed during a part of the second dispensing stroke step for further reducing the volume V to build up pressure for discharge of the dose of substance, or may open at the start of the second dispensing stroke step. When the valve opens the metered dose is expelled or discharged in a suitable receptacle (not shown) .

The next and subsequent dose is drawn along by the negative pressure of the fine-side pressure created during the second dispensing stroke step so that a new dose is continuously made ready for dispensing. Following the second dispensing stroke step the third dispensing stroke step is performed in which the valve 21 closes and the rollers 6a, 6b move apart, as seen in fig. 5, for returning to their starting position in the subsequent fourth dispensing stroke step. As soon, as the rollers move apart the substance from the reservoir 2 proceeds to accumulate again above the closed valve 21 to refill the substance tube 7 in preparation for a new dispensing cycle. The substance tube 7 is thus kept full of substance irrespective of which dispensing step the rollers 6a, 6b are in. Due to the continuous dispensing cycle, the cooperating alternating action of the rollers 6a, 6b and the valve 21 accurate doses of amount can be dispensed at a reasonable speed.

The control of the valve and the rollers may or may not be computerized and selected according to preconditions defined primarily by the characteristics of the individual substance and dispensing speed and amount of dose.

Fig. 6 shows a substance tube 7 provided with a threaded coupling part 22 for screwing on a corresponding part 23 at the outlet 9 of the reservoir 2. Any suitable kind of union fittings, couplings or similar means that provides for easy and fast mounting and replacement of substance tube on the feed reservoir is intended within the scope of the present invention. The parts may be threaded or not as long as the coupling is strong enough to resist the pressure during the dispensing cycle.

Fig. 7 shows a second embodiment 1' for a linear peristaltic dispensing apparatus according to the present invention. The second embodiment corresponds substantially to the first embodiment 1 and for like part same reference numerals are used.

The second embodiment 1' differs from the first embodiment 1 only in the design of the gear transmission and the suspension of the rollers 6a, 6b. In the present case the pinion 15 is kept in a fixed position and the rollers 6a, 6b are suspended in a contrarotable manner on opposing U-brackets 18a, 18b which is secured to the tooth rack 14'. During rotation of the toothed pinion 15, by means of e.g. a servomotor, the teeth of the pinion 15 engage the teeth on the toothed rack 14' causing the rollers 6a, 6b to move up and down to perform the repeated cycle of dispensing strokes. Thus, instead of moving the pinion 15 the rack 14' is moved.

The advantage of using a servomotor in any embodiment according to the present invention is that the translatory movement speed and acceleration of the rollers during the dispensing stroke can be controlled, so that e.g. the various sections of the downwards movement of the rollers are made with different speed. This special feature and advantage in some embodiments of the present invention is better understood from the Table below . Table

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The Table illustrates the dispensing profiles for doses of water and mayonnaise. The relationship between the values of the Table are plotted in fig. 8.

If as shown in the Table and fig. 8 a low viscous substance such as water is dispensed splashing of the dispensed water dose must be avoided. To achieve this, the speed of the translatory movement of the rollers from the first position seen in fig. 3 to the second position seen in fig. 4 is kept low when starting in the first position. Then the speed is increased to increase dispensing rate. When approaching the second position the speed is reduced. If the substance is mayonnaise, i.e. a viscous substance, the starting and stopping of the dispensing stroke is made far more abrupt to promote squeezing action to expel the substance from the discharge end of the substance tube with a certain high pressure, which pressure serves for distributing the dose of substance inside a receptacle and for avoiding heaping. In case heaping is intended, e.g. if the dose of substance is to be dished on a plate in a manner tempting a consumer, heaping can be achieved by reducing translatory speed when the rollers approaches the second position. Nipples may be provided to design the appearance of the heap.

A potato salad containing mayonnaise includes pieces of cooked potatoes, ranging of up to 4 cm in length per piece. In order not to compromise food quality the texture of the cooked potato pieces should be kept intact during dispensing. Thus smashing should be avoided. By carefully adjusting the translatory speed of the rollers and the dispensing stroke cycle the present invention achieve this aim. The gentle treatment of fragile particles is furthermore achieved by the wide dimensions kept through the entire filling system, and by the straight flow, which eliminates turbulence and sharp edges. Fig. 9 shows a schematic flow diagram of the travel paths of the first and second roller, respectively, during the type of cycle of dispensing stroke steps described above with reference to Figs. 5-7. For the sake of illustration, the substance tube and other elements are omitted in Figs. 9-12. In all the latter figures the substance tube should be thought of as extending vertically in between the two travel paths of the respective rollers. In the first step A, A', the two rollers are moved towards each other for compressing the tube. In this step, the rollers move from their respective starting position to their respective upper first position. In the second step B, B' the rollers move from the upper first position to the lower second position. In the third step C, C, the rollers move away from each other for distending the tube. In the fourth step D, D' the two rollers return to their starting position. It is easily seen that the travel path of the first roller ABCD and the travel path of the second roller A'B'C'D' are rectangular.

Fig. 10 shows a schematic flow diagram of the travel paths of the first and second roller, respectively, during an alternative embodiment of a cycle of dispensing stroke steps. In the first step A, A', the two rollers move towards each other to compress the tube at an intermediate third position. In this step, the rollers move from their respective starting position to their respective intermediate third position. In the second step B, B', the rollers move a short distance upwards to the upper first position, thereby preventing excess overpressure in the tube and splashing of substance. In the third step C, C the rollers move from the upper first position to the lower second position for dispensing substance from the discharge opening of the tube (not shown) . In the fourth step D, D', the rollers move away from each other for distending the tube. In the fifth step E, E', the rollers return to their starting position. Fig. 11 shows a schematic flow diagram of the travel paths of the first and second roller, respectively, during another embodiment of a cycle of dispensing stroke steps. In the first step A, A', the two rollers are moved towards each other for compressing the tube. In this step, the rollers move from their respective starting position to their upper first position. In the second step B, B' the rollers move from the upper first position to the lower second position. In the third step C, C the rollers move a short distance upwards to an intermediate fourth position, thereby drawing back a small amount of substance into the tube in a direction opposite the discharge direction. In the fourth step D, D', the rollers move away from each other for distending the tube. In the fifth step E, E', the rollers return to their starting position.

Fig. 12 shows a schematic flow diagram of the travel paths of the first and second roller, respectively, during yet another embodiment of a cycle of dispensing stroke steps. In the first step A, A', the two rollers move towards each other to compress the tube at an intermediate third position. In this step, the rollers move from their respective starting position to their respective intermediate third position. In the second step B, B', the rollers move a short distance upwards to the upper first position, thereby preventing excess overpressure in the tube and splashing of substance. In the third step C, C the rollers move from the upper first position to the lower second position for dispensing substance from the discharge opening of the tube (not shown) . In the fourth step D, D' the rollers move a short distance upwards to an intermediate fourth position, thereby drawing back a small amount of substance into the tube in a direction opposite the discharge direction. In the fifth step E, E', the rollers move away from each other for distending the tube. In the sixth step F, F', the rollers return to their starting position. As becomes obvious from Figs. 10-12 the travel path of the first roller ABCDE(F) and the travel path of the second roller A'B'C'D'E' (F' ) are at least partly rectangular.

Fig. 13 shows two exemplary dosing profiles, i.e. graphs of the speed of roller movement during that part of the dispensing cycle, in which the rollers are pressed together to squeeze the tube, plotted against the elapsed part of the dispensing cycle. In this plot, positive values on the y-axis (ordinate) indicate movements of the rollers in the directon towards the lower second position as described for the embodiment of Fig. 10. In contrast, negative y-values indicate movement of the rollers away from the lower second position and towards the upper first position. It can be seen that for each of the cycles shown in Fig. 13 the rollers, after having moved towards each other for squeezing the tube, first move toward the upper first position (negative y-values) for reducing the excess pressure in the tube. Thereafter, they reverse their direction and move towards the lower second position (positive y-values) for discharging the substance from the tube.

Modifications and variations from the above exemplary embodiments are foreseen within the scope of the present invention. Instead of pumping from a batch reservoir, the substance tube can be connected to a pipeline with the substance coming in a continuous flow. Unless the substance to be dispensed can be compressed to a very high degree a compensator or buffer valve would normally need to be fitted between the substance tube and the pipeline to permit continuous operation. Compensators are known from process lines for dispensing margarine or butter and processed cheese or creme cheese.

Any suitable mechanism that is able to drive the dispensing stroke cycle is forseen within the scope of the present invention, and the person skilled in the art understands that the invention is not limited to tooth bars, gear transmissions and servo motors.

Claims

1. A linear peristaltic dispensing apparatus ( 1 ; 1 ' ) comprising

- a reservoir (2) for a substance to be dispensed, which reservoir (2) has a reservoir inlet (11) and an opposing reservoir outlet (9),

- a substance tube (7) defining a dispensing axis (A), which substance tube (7) has a first end (8) in communication with the reservoir outlet (9), and an opposing discharge end (10) for discharge of an amount of substance, and

- peristaltic means for dispensing the amount of substance out through the discharge end (10) of the substance tube (7), characterised in that - the peristaltic means comprises a first roller (6a), a contra rotating second roller (6b) facing the first roller (6a), and actuator means (5) for moving the rollers (6a, 6b) in relation to the substance tube (7) suspended between the rollers (6a, 6b) .

2. A dispensing apparatus ( 1 ; 1 ' ) according to claim 1, characterised in that the actuator means (5) is adapted to repeat a cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

- a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to an upper first position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7),

- a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b), — a third dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and

- a fourth dispensing stroke step, in which the rollers (6a, 6b) return to their starting position.

3. A dispensing apparatus ( 1 ; 1 ' ) according to claims 1 or 2, characterised in that the actuator means (5) is adapted to repeat a cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

- a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7), - a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the upper first position of the rollers (6a, 6b),

- a third dispensing stroke step, in which the rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b),

- a fourth dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and

- a fifth dispensing stroke step, in which the rollers (6a, 6b) return to their starting position.

4. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claims, characterised in that the actuator means

(5) is adapted to repeat a cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

- a fourth dispensing stroke step, in which the rollers (6a, 6b) move to an intermediate fourth position between the upper first position and the lower second position,

- a fifth dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and

- a sixth dispensing stroke step, in which the rollers (6a, 6b) return to their starting position.

5. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claims, wherein the actuator means (5) is adapted to repeat a cycle of dispensing stroke steps, characterised in that the rollers (6a, 6b) follow along a rectangular travel path at least during part of the cycle.

6. A dispensing apparatus ( 1 ; 1 ' ) according to any of claims 2- 5, characterised in that at least the part of the substance tube (7) subjected to the cycle of dispensing strokes is situated in a vacuum chamber (4) .

7. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claims characterised in that the dispensing apparatus (1) comprises at least one valve (21) for opening and closing the flow passage through the substance tube (7) during at least the dispensing cycle.

8. A dispensing apparatus ( 1 ; 1 ' ) according to claim 7, characterised in that the at least one valve (21) for opening and closing the flow passage through the substance tube (7) is a pair of opposing clamps (21) located distal to the lower second position of the rollers (6a, 6b) .

9. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claims, characterised in that the first end (8) of the substance tube (7) has a first fitting part (22) for coupling to a second fitting part (23) on the reservoir (2) .

10. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claims, characterised in that the substance tube (7) is disposable or reusable.

11. A dispensing apparatus ( 1 ; 1 ' ) according to any of claims 7 - 10, characterised in that at least the operation of the actuator means (5) and/or the at least one valve (21) is controlled by a computer program run on a computer.

12. A dispensing apparatus ( 1 ; 1 ' ) according to any of the preceding claim, characterised in that the dispensing apparatus ( 1 ; 1 ' ) is a vertical or a horizontal linear dispensing apparatus.

13. A dispensing method for dispensing a dose of substance comprising the steps of - mounting a substance tube (7) on a substance reservoir (2) outlet of an apparatus (1) according to any of the preceding claims 1-12, and

- filling the reservoir (2), characterised in that the method further comprises the steps of setting the operational parameters of said apparatus ( 1 ; 1 ' ) , and

- dispensing a plurality of doses or portions of substances.

14. A dispensing method according to claim 13, characterised in that the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

— a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to an upper first position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7),

— a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b), - a third dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and

— a fourth dispensing stroke step, in which the rollers (6a, 6b) return to their starting position.

15. A dispensing method according to claim 13, characterised in that the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

- a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7),

- a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the upper first position of the rollers (6a, 6b),

- a third dispensing stroke step, in which the rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b), - a fourth dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and

16. A dispensing method according to claim 13, characterised in that the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises

- a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to the upper first position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7),

- a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b), — a third dispensing stroke step, in which the rollers (6a, 6b) move to an intermediate fourth position between the upper first position and the lower second position

17. A dispensing method according to claim 13, characterised in that the dispensing takes place in a repeated cycle of dispensing stroke steps, wherein the cycle of dispensing stroke steps takes place along the length (L) of the substance tube (7) between an upper first position of the rollers (6a, 6b) and a lower second position of the rollers (6a, 6b), which cycle comprises a first dispensing stroke step, in which the rollers (6a, 6b) move towards each other from a starting position to an intermediate third position between the upper first position and the lower second position to reduce the gap (G) between the rollers (6a, 6b) and squeeze the substance tube (7), a second dispensing stroke step, in which the contrarotating rollers (6a, 6b) move to the upper first position of the rollers (6a, 6b), a third dispensing stroke step, in which the rollers (6a, 6b) move to the lower second position of the rollers (6a, 6b) , a fourth dispensing stroke step, in which the rollers (6a, 6b) move to an intermediate fourth position between the upper first position and the lower second position, a fifth dispensing stroke step, in which the rollers (6a, 6b) move apart to regain the gap (G) between the rollers (6a, 6b), and - a sixth dispensing stroke step, in which the rollers (6a, 6b) return to their starting position. A dispensing method according to any of claims 14-17, characterised in that the rollers (6a, 6b) follow along a rectangular travel path at least during part of the cycle.