WO2001003817A1

WO2001003817A1 - Water carbonator

Info

Publication number: WO2001003817A1
Application number: PCT/GB2000/002435
Authority: WO
Inventors: James Richard Collin; Peter Carr
Original assignee: Atchison Investments Limited
Priority date: 1999-06-22
Filing date: 2000-06-22
Publication date: 2001-01-18
Also published as: DE20010305U1; GB9914595D0; GB2351243B; AU5833300A; GB2351243A; GB0015326D0

Abstract

A carbonating device including means for connecting a supply (12) of pressurised CO2, means for connecting a container (1) which container (1) can be partially filled with liquid to be carbonated, CO2 delivery means whereby CO2 under pressure can be delivered from said supply (2) to said liquid wherein said delivery means includes a nozzle (5) adapted to be submerged below the said liquid in said container (1) during use of the device and wherein the said nozzle (5) incorporates a variable venturi orifice (6) in the region where the CO2 under pressure is caused to contact the said liquid and the variation of the venturi is adjustable.

Description

WATER CARBONATOR

This invention is concerned with a water carbonator principally for domestic uses. In particular the present invention provides a water carbonating device with several unique features of construction .

Carbonating devices produce water for domestic use in preparing sparkling beverages.

The carbonation process involves introduction of CO- into liquid such as water in a suitably adapted bottle to produce a stable carbonated water. The CO- supply is from high pressure compact cylinders and as such needs to be controlled and directed through valves, conduits and orifices to provide carbonation of water or water- based beverages in a safe, efficient and environmentally friendly manner .

The closest known arrangement of devices according to the present invention are conventional Domestic type carbonator (e.g. those marketed under the Trade Marks Soda Stream or Soda Club) .

These known devices typically have no system to control the gas flow nor provide any useful indication of the degree of carbonation achieved.

The operation of these machines relies on the past experience of the Operator who opens the main gas valve so allowing gas to flow from the gas storage cylinder to the water via a simple orifice without control or indication. This operation is repeated a number of times until the Relief Valve in the body of the carbonator operates, the water having reached its upper carbonation limit whereby further CO_ injections are wasted.

The door, when present, on these known units is hinged to the side and fitted with a simple latching mechanism.

The 'closest' known arrangements just described are associated with a number of significant drawbacks. There is no fine control or indication of Gas Flow. There is no visual indication of Carbonation level, and no Audible Indication of Carbonation level. There is no door or only a hinged door liable to opening in event of failure under pressure of Bottle. Their nozzles are of low efficiency, and a number of critical contact parts are manufactured in Copper Alloy.

The present invention aims to minimise or avoid one or more of the aforesaid drawbacks, as follows.

1. No control of the gas flow other than the operation of the On/Off Gas operating lever. Embodiments of carbonating devices according to the present invention can be fitted with an electronic regulating system, which monitors the duration of the gas flow and indicates when a pre-set value is reached.

No regulation of the gas 'flow, the operation of the Gas Lever gives maximum flow only. Embodiments of carbonating devices according to the present invention can be fitted with a variable annular orifice which allows the operator fine control of the gas flow and hence the quality ('mouth feel', bubble size and distribution) as well as the level of carbonation.

2. where fitted the Door is latched on one edge, the other edge mounting the pivot. In the event of bottle failure the conventional door could become unlatched by the forces exerted by the expanding Gas/Water mixture and burst open, putting the operator at risk from flying debris. Mounting of the hinge to the side of the unit requires a free working area to the front of the body equal to the arc described by the free corner of the door from the hinge.

Embodiments of carbonating devices according to the present invention can be fitted with a rotary door, which is held securely top and bottom at its centre of rotation. In the event of the failure of a bottle, the expanding Gas/Water mixture would exert forces equally balanced about the door's internal face and therefore would not tend to cause the door to spring open.

A further advantage of the Rotary Door is that the movement of the Door when opening is contained within the body of the machine thereby requiring no additional free working space around the door .

No visual indication is given to the operator to indicate the degree of carbonation other than the possible observation of the gas flow in the bottle. Embodiments of carbonating devices according to the present invention can be fitted with an illuminated display which gives progressive indication from bottom (low) to top (high) through green - amber - red L.E.D. as to the level of carbonation. The electronic circuit can also monitor the operational sequence and provide warning in the event of mal- operation of the machine (i.e. holding down the gas lever for too long or operation of the gas lever too many times) .

No Audible indication is given to the operator to indicate the degree of carbonation other than by operation of the conventional relief valve and attendant discharge of excess Gas when maximum carbonation is reached. Embodiments of carbonating devices according to the present invention can be fitted with an electronic sounder, which generates audible signals at each stage of the operation, for example this can be arranged to emit:

Single Beep at each stage of Carbonation, and

Double Beep at required level of Carbonation, and Rapid Multi-Beep if operational error made.

The gas discharge for the aforesaid conventional domestic carbonating devices is from a simple orifice and relies on high energy levels in the gas flow to produce adequate mixing of the CO_ with the water to promote the C0₂ entering solution with the water. This has several disadvantages in that : -

It is not efficient in mixing,

The performance falls off rapidly with reduction of gas pressure, and

Excess gas is used to obtain higher velocities which is then vented to atmosphere, causing CO- wastage and atmospheric pollution,

Embodiments of carbonating devices according to the present invention can be fitted with a Venturi type nozzle, which provides highly efficient mixing over a wider range of pressures thereby maximising use of the contents of each Gas Cylinder.

6. A number of parts that constitute the Gas Train and Nozzle

Assembly are manufactured in Brass (Copper Alloy) . This may lead to copper pick-up in the Carbonated water due to the acidic nature of the water with CO- in solution.

Embodiments of carbonating devices according to the present invention can be manufactured throughout in Food Grade Plastics and Stainless Steel.

According to a first aspect, the present invention provides a carbonating device including means for connecting a supply of pressurised CO- , means for connecting a container which container can be partially filled with liquid to be carbonated, CO„ delivery means whereby C0_ under pressure can be delivered from said supply to said liquid wherein said delivery means includes a nozzle adapted to be submerged below the said liquid in said container during use of the device and wherein the said nozzle incorporates a variable venturi orifice in the region where the C0„ under pressure is caused to contact the said liquid and the variation of the venturi is adjustable.

The Nozzle design of embodiments of device according to the first aspect is based upon the Venturi Principle, whereby the shaped jet formed by the discharge of a primary motive fluid (Gas or Liquid) 'from' a nozzle, will if directed through a suitable orifice generate an area of low pressure. This will entrain a secondary base fluid (Gas or Liquid) and discharge the mixture of base and motive fluids from the downstream face of the orifice.

In these embodiments where the preference is to encourage the rapid absorption of CO- in potable water to provide Carbonated Water for Soft Drinks, the following benefits can be experienced: a) High Turbulence mixing of the two fluids (CO- and water) which will promote the absorption of the C0_ by the water,

b) Generation of low pressure in the water interface will provide for de-aeration of the water and allow for greater CO, dissolution,

c) The generation of a 'plume' of gaseous liquid rich in CO which will scourge the whole of the container and contents so promoting maximum absorption of the available CO-, and

d) The design of the nozzle/orifice arrangement promotes the formation of smaller bubbles of CO- so allowing more effective absorption of the CO- by the water due to the increased surface area/volume ratio achieved. Secondarily, the smaller bubbles will tend to rise through the water at a lower velocity so allowing more time for the absorption of the CO- by the water.

e) Due to the highly efficient manner in which the liquid is carbonated the CO- is taken up as a stable constituent of the solution. This has the effect of allowing pre-mixed drinks, infusions and solutions to be used i.e. it is possible to carbonate for example: Iced Tea, Iced Coffee, Wines, Flavoured Waters, Juices etc.

According to a second aspect, the present invention provides a carbonating device including means for connecting a supply of pressurised CO- , means for connecting a container which container can be partially filled with liquid to be carbonated, CO- delivery means whereby CO- under pressure can be delivered from said supply to said liquid wherein said delivery means includes a nozzle adapted to be submerged below the said liquid in said container during use of the device and wherein the device includes a door member rotatably mounted within the device for rotation about a substantially vertical axis to open the device by rotation to a first position for container insertion or removal and close the device by rotation to a second position for carbonation of the liquid. The door design of embodiments according to the second aspect is preferably based on a rotating semi-circular tube, associated with a number of benefits:

a) The operational footprint of the machine is smaller than if fitted with a hinged door and the movement of the door is contained within the machine base.

b) In the event of a bottle exploding whilst liquid is being charged with CO- the door will absorb the impact directly and be supported by bearings mounted in the main frame. Failure of a door catch would not allow fragments of the bottle to escape, as would be the case with a hinged door.

c) When the charged bottle is released it discharges a small puff of wet vapor, which is contained within the inside of the rotary door and is easily accessible for cleaning.

The spray does not contaminate the rear and sides of the charging chamber, which are not readily accessible and are therefore difficult to clean.

A Gas Flow regulator can be incorporated into the machine so allowing more accurate control of the degree of carbonation.

This will provide for the following benefits-.- Improved control of the degree of carbonation, a facility to pre-set the regulator allows for repeatable and consistent levels of carbonation to be achieved; and the increased level of control will provide for more economic use of the co₂.

According to a third aspect we provide a device according to the first and/or second aspects incorporating a visual indicator adapted to indicate by visual means, the degree of carbonation achieved in use.

The design of the machine can incorporate a micro processor controlled, variable level, visual display as to the level of carbonation achieved. This will provide the following benefits:- A Sensor provides a visual indication through the use of suitable circuit and L.E.D. of CO- being available from the cylinder, progressive illumination of the display will give visual guidance to hearing impaired users as to the level of carbonation. The 'stepped' electronic 'bleeper' which works in tandem with the LED circuit will give audio indications of levels achieved to visually impaired users, and illumination of the pre-set display will provide an indication that the desired level of carbonation is achieved without the requirement to cause the relief valve to blow- off, so allowing more economic use of the CO- and reducing the potential for the discharge of C0_ to atmosphere.

The inclusion of audible and visual signals together with the use of tactile markings on Selector Button [9] and Adjustable Nozzle [5] ensure that this machine is suitable for safe and efficient operation by people with Visual or Aural impairment .

According to a fourth aspect we provide a device according to the first and/or second and/or third aspects incorporating an audible indicator adapted to indicate by audible means, the degree of carbonation achieved in use.

In addition to the essential features of the device detailed in the above-specified aspects of the invention, the following features which whilst benefiting the manufacture and performance or the unit are nevertheless preferably incorporated.

(1) The design of the gas path is variable and as such a degree of control may be exerted over the size and distribution of C0- 'bubbles' . This gives a different 'mouth feel' for the customer with the larger bubbles giving a sharp aggressive sensation, whilst the smaller bubbles give a softer natural sparkle.

(2) The use of stepped latches for accurate location and pre-loading of springs allows for a commonality of parts in that a single specification of spring may be utilised for a number of different func ions . (3) The use of high density plastic material finished to a very high surface polish serves to ensure that the device is easy to clean, resistant to staining and will remain in a sterile condition for longer .

(4) Specialised treatment of the plastic during manufacture and moulding in relation to the build-up of Static charges ensures that the device will tend to repel dust and other airborne particles, thereby maintaining clean and hygienic surfaces.

(5) The design of the device giving a broad base coupled with a low centre of gravity provides a stable operating system.

(6) A snap- lock construction minimises the requirement for threaded fasteners and adhesive securing systems during construction. This gives savings in both materials and labour. In addition a further environmental benefit is enjoyed in that no solvents are required for cleaning and/or curing of adhesive systems.

(7) The use of H.T. (High Tensile) Engineering grade plastics combined with the unique Stressed Rib construction allows for appreciable savings in material. This therefore gives consequential savings in; Energy, Raw Material and Transport Costs.

(8) The use of Identified, Virgin Plastics ensures that at the end of the working life of any device all parts may be readily identified and re-cycled.

(9) The savings in energy and materials during construction and shipping together with the high efficiency use of CO- during operational life, along with the ease of re-cycling when the unit is to be disposed of, ensure that the device is environmentally friendly .

(10) The use of a machined Metallic Insert in the Gas Valve allows for greater accuracy in the location of the gas cylinder. The use of this insert also provides for greater safety margins with reference to the misuse of the appliance by the end user or by the use of gas cylinders with damaged threads.

(11) The use of corrosive resistant Stainless Steel for the springs provides for long life and accurate repeatability of all Spring operated functions.

(12) A two-part construction of the Bayonet Fitting for receiving the threaded water bottle allows for the manufacturing of the parts utilising the simplest of patterns and moulding machines (no Side Cores) . This unique design also provides for additional rigidity within the Bayonet, providing a more accurate location of the Bottle and a better gas seal.

In order that the invention in its several aspects may be illustrated, more easily appreciated and readily carried into effect by those skilled in the art, embodiments thereof will now be described by way of non- li-iting examples only, with reference to the accompanying drawings, in which:

Figure 1 is a cross section through a central plane of the device,

Figure 2 is a sectional view from above, of figure 1, shewing internal components,

Figure 3 is a front elevation, of Figure 1,

Figure 4 is an underneath plan view, (partial cross section)

Figure 5 is a side elevation,

Figure 6 is a plan view form above, of figure 5,

Figure 7 is a front elevation of Figure 5,

Figure 8 is an enlarged cross sectional detail of the sparger venturi nozzle, during operation

Figure 9 illustrates one preferred form of gaseous flowmeter,

Figure 10 illustrates one preferred form of liquid level sensor,

Figure 11 shows the carbonating device in conjunction with a detachable base unit enclosing an auxiliary (reception) chamber,

Figure 12 shows one suitable form of cathodic reservoir, for inclusion within the detachable base unit of Figure 11,

Figure 13 shows a preferred form of refridgerant cooling circuit, and

Figure 14 shows one suitable circuit diagram for the electronic circuit including the microprocessor. Water Carbonating Device - key to Figures 1-7 1. Bottle (Water) 100ml (la) - 500ml

2. Gas Cylinder

3. Gas Valve

4. Restriction Orifice

5. Adjustable Nozzle 6. Nozzle Venturi

7. Bottle Seal

8. Gas Lever

9. Selector button

10. Rotary Door

11. Bayonet Fitting

12. Door Release Button

13. Door Release Latch

14. Gas Sensor Switch

15. Interlock Bar

16. Vent Valve

17. Relief Valve

18. Visual Display

19. Electronic Sounder

20. Sparger 21. Gas Pin

22. Back Cover

23. Main Body

24. Top Cover

25. Lever Cam

Referring to the drawings and initially figure 1, the structure and function of the illustrated device is as follows :

The Back Cover (22) is removed and a full Gas Cylinder (2) is fitted to the Gas Valve (3) mounted at the top, rear of the Main body (23) , below the Top Cover (24) . The Water bottle (1 or la) e.g. 1000ml or 500ml is filled to the correct level and fitted into the Bayonet Fitting (11) thereby forming a gas tight seal with Bottle Seal (7) . With the Rotary Door (10) closed, the Door Release Latch (13) returns to the operational position so allowing Vent Valve (16) to re-seat. The operator selects the Gas flow requirement by use of the Selector Button (9) . The Operator presses Gas Lever (8) which causes Gas Pin (21) to open the Gas Valve (3) and so allows Gas to flow from the cylinder (2) through the Restriction Orifice (4) to the Sparger (20) via a flexible connector. The flow of C0_: is regulated through the adjustable nozzle (5) before entering the Nozzle Venturi (6) here it mixes with the water contained within the water bottle 1 or la. The operation of the Gas Lever (8) also activates the Gas Sensor Switch, which transmits a signal to the Microprocessor. The Microprocessor processes this signal together with the input from the Selector Button (9) . When the selected gas level is achieved the Microprocessor activates the Electronic Sounder (19) and at the same time causes the Visual Display (18) to illuminate to level one (Green L.E.D. illuminated), the Operator observes these signals and releases the Gas Lever (8), this shuts off the gas flow and re-sets the Gas Sensor Switc (14) for the second level of Carbonation. To achieve the second level of Carbonation, the Operator presses the Lever (8) for a second time and the gas flow is re established together with the signal to the Microprocessor. When the selected second degree of carbonation is achieved, the Microprocessor again activates the Electronic sounder (19) and at the same time causes the Visual Display (18) to illuminate to level two (Amber L.E.D. illuminated). The Operator observes these signals and releases the Gas Lever (8) . This shuts off the Gas Sensor Switch for the third level of carbonation. To achieve the third (selected) level of carbonation the operator presses the Gas Lever (8) for a third time and the gas flow is again-re-established together with the signal to the Microprocessor. When the third (selected) degree of carbonation is obtained, the Microprocessor again activates the Electronic Sounder (19) which generates a rapid series of 'bleeps' and at the same time causes the Visual Display (18) to illuminate to third (finished) level (Red LED illuminated) . The water is now at the correct pre-selected level of carbonation, if the Operator then attempts to over- carbonate the water the Microprocessor will go into alarm condition and cause all of the L.E.D. to flash rapidly and the Electronic sounder to bleep rapidly and repeatedly.

Further Variation to the degree of carbonation and associated 'mouth feel' may be achieved by adjustments made to the variable orifice fitted to the end of the Sparger. When the carbonation is completed the Operator depresses the Door Release Button (12) which through the operation of Lever Cam (25) relieves the pressure in the bottle (1) through the Vent Valve (16) to atmosphere. In the event of over pressurising of the bottle (1), the Vent Valve (16) will automatically open at 6.0 bar, if the pressure continues to rise then the Relief Valve (17) will automatically open at 8.0 bar .

These Valves (Vent [16] and Relief [17] are factory set cartridge units and are to provide for safe and accurate pressure relief and protection for the Bottle [l]and Operator. In the event of bottle manufacturing and design improvements these valves may be replaced by the factory modified units. The advantage in this design is safe and repeatable pressure relief and protection against operator abuse.

With the Door Release button (12) depressed and the Vent Valve (16) open then the Rotary Door (10) is free to open. In the process of opening, the rotary Door (10) locks the Door Release Latch (13) in the open position this in turn locks the Vent Valve (16) in the open position thereby ensuring that no pressure build-up can occur in the bottle when the Rotary Door (10) is open.

A further design safety feature is the incorporation of a double prong Interlock Bar (15), this locks the Gas Lever (8) in the up position so preventing inadvertent discharge of C0₂ whilst the Rotary Door (10) is open.

Gas flow - a volumetric and/or mass flow measuring device is incorporated into the gas path. This is to measure accurately the actual amount of gas transferring from the cylinder [2] to the bottle [1] independently of the manner by which the machine is operated. This information is then processed by the Electronic circuit (see Figure 14) to provide (i) an indication of carbonation level reached and (ii) to operate a cut-off device to stop the flow of gas at the operator's pre-programmed level. The incorporation of one possible volumetric flow measuring device 32 is shown schematically in the accompanying Fig. 9.

The device consists of a fixed chamber 33 with connections for the input 34 and outflow 35 of the gas together with connections to the microprocessor 39. The device 32 is located in the gas flow path 45 downstream of the gas valve (not shown in Fig. 9) .

The sensor is primarily an axial flow turbine rotor 40, fitted with a gas pressure sensitive, spring 44 loaded brake 41. The Blade tips 42 of the rotor 40 are implanted with magnetic elements 43 and the fixed chamber 33 incorporates a suitable sensor 44. The number of pulses generated is directly proportional to the gas flow and is independent of the time and pressure of the gas flow. The pulses generated are monitored and processed by the microprocessor 39. When the selected amount of gas flow has been achieved, the microprocessor 39 activates the circuit (36,37,38) and causes the audible and visual indicators (not shown in Fig. 9) to be activated to indicate that the correct amount of gas has been injected into the beverage.

The pressure sensitive brake 41 is de-activated by the application of the gas pressure to the front of the turbine rotor 40; this serves to disengage the rotor 40 from the friction brake 41 in the front housing 33. Disengagement of the brake allows the rotor to spin freely under the action of the gas flow. When the gas flow ceases and pressure is no longer applied to the front face of the turbine rotor, the brake re-activates. The brake then stops the turbine rotor from running on due to the inertia of the rotor after the gas flow has ceased.

The sparger [20] can incorporate a temperature sensor, usefully positioned at its lower end to monitor actual temperature of liquid in the bottle [1] . The temperature of the water can be displayed on an alpha-numeric display screen for the information and benefit of the operator. The sensor can be incorporated into the body of the sparger at a point below that of the normal fill level. In the event of the water level being below the normal fill level, the level sensor would block the temperature display so ensuring no spurious temperature display at low levels, since the temperature sensor would be measuring the head space temperature above the water.

The signal flow from the temperature sensor can be processed by the microprocessor and then displayed in a number of ways : a) solid state alpha-numeric screen, and/or b) red (warm), blue (cold) L.E.D, and/or c) frequency modulated signal to the electronic sounder to produce a variable pitch tone (low for cold, high for warm) . This audible signal would serve to warn those users who are visually handicapped of the correct functioning of the unit .

This audio/visual indication is preferably common throughout the machine functions and serves to ensure that the specific needs of the audio or visually impaired user are best catered for.

The temperature of the liquid to be carbonated is one of the control parameters during the carbonation operation, therefore this information can also be processed by the electronic circuit (see Figure 14) and used as a secondary control function to ensure the correct degree of carbonation at all temperatures.

The sparger [20] incorporates a liquid level detector as depicted so that in the event of no liquid/low liquid; the level detector signal is processed by the electronic circuit to block the gas flow, at the same time advising the operator of the low level condition.

As shown in figure 10, the sensor consists primarily of a linear resistor 46 insulated from the return leg 47. A section 46 of the resistor would be exposed to contact with the water contained within the bottle. The liquid would, depending on the fill height, make the final link between contacts (46,47) thereby establishing a circuit. The resistance value is proportional to the liquid level (49,50) contained within the bottle (not shown in Figure 10) . The value of the resistance of the circuit is monitored by the microprocessor 39, which in the event of the liquid level being outside (high or low) of the operational parameters (49,50) signals the fault to the operator through both visual and audible means (not shown in Fig. 10) .

A pressure sensor is installed within the head space above the liquid level contained in the bottle, to monitor the pressure in that head space. The signal generated can be processed by the electronic circuit (see Figure 14) e.g. the same microprocessor and used as a further control- parameter for the carbonation level. It can also function as a secondary control to prevent door opening before the head space is vented. In order for this to be carried out, the sensor can be of the piezo electric type incorporated into the non- functional end of the relief valve chamber. The output from the pressure sensor would be processed by the same microprocessor and the information generated displayed for the operator. In the event of a pre-programmed over-pressure being generated, the operator's attention would be attracted by visual and audible alarms prior to the relief valve setting being attained. The information gathered from the monitoring of the pressure in conjunction with the monitoring of the temperature would be used by the microprocessor to calculate the degree of carbonation achieved within the liquid being carbonated. This value would then be displayed so that the operator would as a result be able to achieve more consistent results independent of the gas and water supply conditions.

A reception chamber can be incorporated into the rear of the unit, adjacent to the C0₂ cylinder, of an equivalent volume to the water bottle.

The carbonating device can be fitted with such an auxiliary chamber designed for the reception, treatment and holding of an equivalent (plus working allowance) amount of water as is contained within the bottle (1) . This chamber can be formed within the detachable base unit 51 as depicted in figure 11.

The chamber incorporates a self-contained cartridge type filter/softener unit, which will pre-treat the water prior to it entering the chamber. The filter will remove gross debris and organic materials with specific filter elements being available for de-chlorination, de-fluoridation and the like. A reverse osmosis filter element can be used to remove trace materials (Lead, Copper, Nitrates etc.).

The base unit 51 is secured to the carbonator with cam- lock clips 52. The water reservoir is connected to the bottle 1 through an auxiliary filling line equipped with push fit connectors at the junction between carbonator and base unit 51. This facilitates direct transfer of treated water from the base unit 51 to the carbonation device.

The motive power for transfer of water from the reception chamber to the water bottle can be a regulated flow of C0₂ from the C0₂ Cylinder. This will give the additional benefit of pre-carbonating the water by surface absorption.

The reception chamber of Figure 11 can be fitted with suitable silver alloy cathodes, to ensure the water processed by the machine would be maintained in a suitable sterile condition. In order to achieve this, reference is made to Figure 12.

The auxiliary chamber just described with reference to Figure 11 can contain a silver alloy element to be charged by an electric current to ensure the silver element acts as the cathode within the system as shown schematically in Figure 12. With the silver element in a cathodic state, a release of silver ions will occur. These silver ions have a unique biocide effect on the water and will ensure that no unwanted organic or biological action will occur within the reservoir, and without recourse to the use of environmentally unfriendly chemical dosing. The chamber can incorporate a reservoir 53 constructed of a flexible membrane, coated internally with a conductive material 54 to act as the anode. The silver element cathode 55 is insulated from the membrane 53. The conventional direction of the anode current is from the positive anode to the cathode but it is to be understood that the anode current is actually a movement of electrons counter to this i.e. from cathode to anode.

The reception chamber can be fitted with a high efficiency heat exchanger. This could be implemented by a suitable refrigeration circuit to ensure that the water to be processed in the machine is cooled to the operator's requirements (normally 10 °C) . This would confer the additional benefit of improving the take-up of CO_: , conferring increased efficiency of the system. In order to achieve this, reference is made to the accompanying figure 13.

The auxiliary chamber just described with reference to figure 11 can also contain a suitable heat exchanger 56 (evaporator/reservoir) supplied with a refridgerant for the purpose of cooling the water in the reservoir to a preferred temperature of 10 °C (or below) . The refridgerant system can be based on the thermal compression cycle, powered 58a by a self regulating high efficiency heater/compression unit 57. The heat exchanger can be formed from small bore tube plated with silver alloy and so may act as the cathode described with reference to figure 12. The condenser 58 can be a high efficiency, natural draft, counter-current unit fitted with an auxiliary fan 59 for high duties. The circuit preferably includes an expansion valve 60.

Advantages of embodiments of the present carbonating machine include: variable control of gas flow, high efficiency venturi nozzle (effective on wider pressure range) , visual indication of carbonation level, audible Indication of carbonation level, rotary door (increased safety factor, reduced 'footprint'), ease of manufacture (snap-lock fitting of parts), ease of recycling at end of life (identified virgin plastics) , reduction of C0₂ pollution (no venting off during operation) all contact parts manufactured in food grade material, and hygienic design and finish.

Embodiments of the invention can take different sizes of gas cylinder 2. The gas valve 3 comprises a moulded shroud 3a within which an appropriate screw threaded insert (not shown) can be integrally moulded. The thread can be modified by use of a double -threaded adaptor (not shown) which locates into the screw threaded insert, providing the required thread for other types of cylinder. If necessary, for the purpose of using a larger type of gas cylinder than the one schematically illustrated in Figure 1, the casing can be adapted. For example part of the inside of the rear cover can be cut away without affecting the overall function and performance of the carbonating device.

Claims

1. A carbonating device including means for connecting a supply of pressurised C0₂ , means for connecting a container which container can be partially filled with liquid to be carbonated, C0₂ delivery means whereby C0₂ under pressure can be delivered from said supply to said liquid wherein said delivery means includes a nozzle adapted to be submerged below the said liquid in said container during use of the device and wherein the said nozzle incorporates a variable venturi orifice in the region where the C0₂ under pressure is caused to contact the said liquid and the variation of the venturi is adjustable .

2. A device as claimed in claim 1 further incorporating a system for controlling the gas flow, such as a volumetric and/or mass flow measuring device coupled with a regulator.

3. A device as claimed in claim 1 or 2 adapted to provide a visual and/or audible indication of the degree of carbonation achieved, such as by means of coloured light emitting diodes and/or electronic sounder as part of an electronic circuit.

4. A device as claimed in claim 2 in which said system is an electronic regulating system which monitors duration of gas flow and indicates when a pre-set value is reached.

5. A device as claimed in any preceding claim in which the venturi orifice is a variable annular orifice allowing fine control over the gas flow.

6. A device as claimed in any preceding claim further including a rotary action door held securely at its centre of rotation.

7. A carbonating device including means for connecting a supply of pressurised C0₂ , means for connecting a container which container can be partially filled with liquid to be carbonated, C0₂ delivery means whereby C0₂ under pressure can be delivered from said supply to said liquid wherein said delivery means includes a nozzle adapted to be submerged below the said liquid in said container during use of the device and wherein the device includes a door member rotatably mounted within the device for rotation about a substantially vertical axis to open the device by rotation to a first position for container insertion or removal and close the device by rotation to a second position for carbonation of the liquid.

8. A device as claimed in claim 7 in which the door is in the form of a rotating semi-circular tube.

9. A device as claimed in any preceding claim incorporating a two-part construction of bayonet fitting for receiving the water bottle.

10. A device as claimed in any preceding claim including a temperature sensor incorporated within the vicinity of said nozzle .

11. A device as claimed in any preceding claim further including a water level sensor and/or a pressure sensor.

12. A device as claimed in any preceding claim further including a reception chamber adapted to receive an additional volume of water and optionally incorporating a flexible membrane reservoir.

13. A device as claimed in claim 12 in which the reception chamber is fitted with silver or silver alloy electrodes.

14. A device as claimed in claim 12 or 13 in which the reception chamber is adapted to cool water to be processed in the device .

15. A device as claimed in any preceding claim in which the gas cylinder locates into a threaded insert provided within a moulded shroud attached to the incoming gas valve.

16. A device as claimed in claim 15 in combination with at least one double threaded adaptor which can locate within said threaded insert to provide an alternative thread for accommodating gas cylinders of different size and/or type.