GB2385291A

GB2385291A - Liquid dispenser with capillary outlet

Info

Publication number: GB2385291A
Application number: GB0203520A
Authority: GB
Inventors: John Nicholas Reid
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-14
Filing date: 2002-02-14
Publication date: 2003-08-20
Also published as: AU2003209979A1; GB0203520D0; WO2003068664A1

Abstract

A machine suitable for dispensing a beverage comprises a reservoir 10 suitable for storing a liquid that supports microbial growth, such as fresh milk or fruit juice, connected to an outlet in the form of capillary tube 18, positioned to a aim a fine jet of liquid into a dispensing container 30. Means such as a solenoid actuated hammer or piezoelectric crystal, to shake or flick the capillary 18 after dispensing, may be provided, such as to prevent drop formation at the end of the capillary 18. An airlock 22, and oxidizing gas such as from an ozoniser 26 may be provided to sterilise the capillary 18. The liquid may be stored in a collapsible container 10 which reduces in volume as the liquid level falls, such that the liquid is not exposed to air at any point within the container 10. The machine may further feature a peristaltic pump arrangement 16. The machine may be suitable for use in coffee and tea making, with fresh milk. As only a very tiny residue of meniscus of liquid may form at the end of the capillary, the possibility and severity of any milk going off may be substantially reduced.

Description

DISPENSING MACHINE The present invention relates to a machine for dispensing beverages containing a liquid, such as milk or fruit juice, that supports microbial growth.

Vending machines have not yet proved successful in dispensing drinks, such as tea or milk shakes, that require milk in liquid form. Though coffee can taste acceptable when made with powdered milk, the same does not apply to tea and for this reason far more coffee is sold by automatic vending machines than tea. Even the taste of coffee can be improved by the use of fresh instead of powdered milk. Despite the demand, no vending machine has yet been able to use fresh milk as an ingredient, on account of hygiene.

To avoid bacterial infection, milk and fruit juices cannot be left exposed to untreated ambient atmosphere, not even as a thin film nor small droplets. Another problem with milk in particular is that it curdles and if an oxidising gas is used to sterilise the dispensing machine between vending cycles or at regular intervals, the gas tends to accelerate the curdling of the milk.

The invention seeks therefore to provide a machine that can enable milk or another liquid that supports microbial growth to be dispensed in a beverage while maintaining safe standards of hygiene.

According to the present invention, there is provided a machine for dispensing a beverage comprising a reservoir for storing a liquid that supports microbial growth connected to a delivery outlet that is constructed as a capillary tube positioned to aim a fine jet of liquid directly into a dispensing container.

In the invention, the liquid that supports microbial growth, which will hereinafter for convenience be taken to be milk, does not come into contact with untreated ambient air while in the reservoir nor on its way to the dispensing outlet. On leaving the delivery outlet, the milk does not come into contact with any part of the machine and is instead delivered directly into the dispensing container.

Between dispensing cycle, the only part of the milk that is exposed is the tiny surface of the milk within the capillary tube, which resembles a hypodermic needle and is typically less that lmm across. Because of the very small dimensions of this surface, the risk of bacterial infection is minimised.

In order to avoid any risk of a droplet of milk collecting at the bottom of the capillary tube, it is possible to shake or flick the tube to dislodge any such droplet. To this end, a mechanical shock could be imparted to the capillary tube by a small solenoid actuated hammer or a vibrator, such as a piezoelectric crystal, may be coupled to the capillary tube.

Despite the small size of the delivery outlet, it would not be safe to leave milk in it exposed to the ambient atmosphere for extended lengths of time. It is preferred to sterilise the delivery outlet either at regular intervals, such as at the end of each day, or after each prolonged period of non-use, by exposing the delivery outlet to an oxidising gas. The oxidising gas is preferably ozone, which can be generated within the machine by the use of a spark or ultraviolet light, but it would be alternatively possible to use chlorine dioxide. In this case, if exposed milk at the tip of the delivery outlet should become rancid as a result of being exposed to the oxidising gas, its mass will be negligible and it would not affect the taste of the dispensed beverage.

Conveniently, the machine comprises a sterilising chamber that can surround the delivery outlet and that is filled with the oxidising gas. This avoids the sterilising gas coming into contact with other parts of the machine, where it could cause serious corrosion, especially to components made of metal or some plastics materials.

The milk could be stored in a container having a closed ullage space, the gas within which is sterilised. It is preferred, however, to store the milk in an airtight chamber that reduces in volume as milk is withdrawn from it, so that the milk does not have a surface exposed to air.

The airtight chamber could be defined by a moving piston, but it is preferred to store the milk in a flexible plastics sachet that collapses as milk is withdrawn from it.

Such a construction allows for simpler maintenance as it only requires the spent sachet to be removed and replaced by a new one each time that the milk supply is to be replenished.

It would be possible to increase the chamber pressure, such as by moving the piston or compressing the sachet in order to expel the milk. It is preferred, however, to draw the milk from the chamber using a peristaltic pump. Such a pump may comprise a tube of soft silicone rubber that can be replaced or sterilised each time the milk supply is replenished. Such a pump can also be used to draw in a cleaning fluid, such as hot water, to be pumped through the capillary to clean it of any build up of dried or old deposits. At the same time, the delivery outlet can also be replaced. As hypodermic needles are sufficiently inexpensive to be disposable, there is no need for them to be sterilised and recycled.

The invention will now be described further, by way of example, with reference to the accompanying drawing which is

a schematic drawing of part of a beverage dispensing machine of the invention, in which the various parts are not drawn to scale.

The illustrated beverage dispensing machine is intended for hot drinks such as tea or coffee containing fresh milk.

The hot tea or coffee is prepared using conventional equipment either by pouring an instant (totally soluble) powder into the dispensing cup 30 and adding hot water through a spout 20 or, more preferably, by passing hot water through a bag containing powdered coffee beans or tea leaves and delivering the brewed beverage to the dispensing cup through the spout 20. The present invention is not concerned with the manner in which the hot beverage is prepared and for that reason the components that are used in preparing the beverage will not be described in more detail.

The invention is intended to permit fresh milk to be added to the hot beverage in the dispensing cup 30 and to this end fresh milk is stored in the dispensing machine in a collapsible sachet 10. The sachet 10 is coupled through a suitable connector 12 to a flexible silicone tube that is threaded through a peristaltic pump 16. The mechanism of the pump 16, which is represented schematically in the drawing, comprises a rotor with three rollers that pinch the tube 14 as the rotor rotates and squeeze the milk along the tube by peristaltic action. The opposite end of the tube 14 is connected to a delivery outlet 18, constructed as a capillary tube resembling or constituted by a hypodermic needle.

When milk is to be added to the contents of the cup 30, the pump 16 is driven to draw milk out of the sachet 10 and inject it under pressure through the delivery outlet 18 into the cup. Because the milk enters the cup 30 at a high speed, it also acts to stir the liquid in the cup and this

action can be enhanced by intentionally pointing the outlet 18 so that the jet enters the cup tangentially.

An advantage of using a peristaltic pump is that the quantity of milk delivered can be accurately metered. This is because each full rotation of the pump rotor will displace from the sachet a volume equal to the length of the perimeter of the circle traced by the rotor multiplied by the internal cross-sectional area of the tube 14. A stepper motor can thus be used to drive the rotor of the pump to dispense the quantity required.

As can be seen, the milk only passes from the sachet 10 and along the tube 14 on its way to the cup and does not come into contact with any other part of the machine. This greatly simplifies maintaining hygienically safe conditions within the machine.

At the end of each dispensing cycle, a vibration is imparted to the delivery outlet 18 to shake off any droplet of milk that may collect at the bottom of the capillary tube. This vibration can be applied by a vibrating crystal or by a solenoid operated hammer, neither of which is shown in the drawing. Thus the only surface of the milk left exposed to ambient air is the tiny meniscus within the capillary tube. During the course of a day when the machine is in regular use this exposed surface will be constantly replaced and will not remain static for sufficient time for bacteria to grow.

At the end of each day, or after any prolonged period of non-use of the machine, steps are taken to sterilise the capillary tube 18. This is achieved in that the capillary tube 18 is contained with a clamshell casing 22 which is normally open for milk dispensing operation but can be closed to form an air lock around the capillary tube 18.

The air lock 22 is also shown as enveloping the spout 20 but

this is not essential as, depending on the construction of the dispensing machine, the spout may either be absent altogether or it may be used only for carrying boiling or hot water.

With the air lock 22 closed, a pump 24 is used to circulate air through the air lock 22 and into the carbon filter 28. The ozonizer 26 produces ozone by means of a spark discharge or ultraviolet light. In this way, ozone is introduced into the air lock 22 to sterilise the delivery outlet 18 and thereafter the ozonized air is passed through the carbon filter 28 to neutralise the ozone before the air is returned to the pump 24 for recycling or routed, as sterile air to a rigid milk container as ullage for the volume dispensed.

The ozone acts to kill any bacteria on the milk meniscus in the capillary tube and any part of the capillary tube not filled with milk. The air lock 22 and the carbon filter ensure that the ozone (which is corrosive) remains confined to the delivery outlet 18 and is not discharged to the ambient atmosphere nor allowed to attack other internal parts of the dispensing machine. The ozone may cause the milk in the capillary tube to curdle but the curdled milk is not harmful and its mass is too small to affect the taste of the beverage dispensed in the next operating cycle.

When the milk runs out, or at the end of the safe shelf life of the milk, the sachet 10 is simply replaced. At the same time, the tube 14 can be removed for sterilisation and a replacement tube complete with connector 12 fitted to the new sachet 10. The delivery outlet can also be sterilised but if a hypodermic needle is used, it is sufficiently inexpensive to be disposable.

This replacement of the milk supply ensures the total sterility of all the components in contact with the milk can be carried out quickly and effortlessly.

Claims

1. A machine for dispensing a beverage comprising a reservoir for storing a liquid that supports microbial growth connected to a delivery outlet that is constructed as a capillary tube positioned to aim a fine jet of liquid directly into a dispensing container.

2. A dispensing machine as claimed in claim 1, wherein in order to avoid any risk of a droplet of liquid collecting at the bottom of the capillary tube, means are provided to shake or flick the tube to dislodge any such droplet.

3. A dispensing machine as claimed in claim 2, wherein a solenoid actuated hammer is provided to impart a mechanical shock to the delivery outlet.

4. A dispensing machine as claimed in claim 2, wherein a piezoelectric crystal is coupled to the delivery outlet to dislodge any liquid droplet by vibrating the outlet.

5. A dispensing machine as claimed in any preceding claim, comprising means for sterilising the delivery outlet by exposing the delivery outlet to an oxidising gas.

6. A dispensing machine as claimed in claim 5, wherein the oxidising gas is generated within the machine by the use of a spark or ultraviolet light.

7. A dispensing machine as claimed in claim 5 or 6, wherein the machine comprises an air lock that can surround the delivery outlet and that is filled with the oxidising gas.

8. A dispensing machine as claimed in claim 5 or 6 in which air that has been sterilised by the sterilising gas is used as ullage to displace a volume of liquid dispensed from a non collapsing container.

9. A dispensing machine as claimed in any preceding claim, wherein the liquid is stored in the machine in an airtight chamber that reduces in volume as liquid is withdrawn from it, so that the liquid does not have a surface exposed to air.

10. A dispensing machine as claimed in claim 9, wherein the airtight chamber is formed by a flexible plastics sachet that collapses as liquid is withdrawn therefrom.

11. A dispensing machine as claimed in claim 9 or 10, wherein a peristaltic pump is provided to draw the liquid from the chamber.

12. A dispensing machine as claimed in claim 11, wherein the peristaltic pump can be switched to draw a cleansing or sterilising fluid from an external source and pump it through the dispensing capillary tube.

13. A dispensing machine constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.