TECHNICAL FIELD

This invention relates to dispensing apparatus, and is particularly concerned with dispensing of a feedstock so as to deliver a volume of diluted feedstock in a fluid carrier. Methods related to dispensing are also disclosed, along with a preferred dispensing nozzle.

BACKGROUND TO THE INVENTION

In order to dispense certain drinks economically, such as in coin operated machines, a container of such feedstock is provided from which a measured amount is dispensed for mixing with a diluent, such as water. A dispensing machine may provide several sources of feedstock, for example in concentrated form, so as to allow a choice of drinks to be provided.

Such machines can be compact and provide many drinks before servicing is required. Typically the diluent (water) is supplied from the public network, and may be filtered, cooled or heated, as required.

For reasons of health and safety, dispensing systems must be arranged to avoid contamination, and must not facilitate the growth of harmful organisms. Ideally some form of self-cleaning is desirable so as not to require the attentions of a cleaning person who may themselves accidentally introduce contamination during a cleaning procedure.

SUMMARY OF THE INVENTION

According to the invention there is provided a mixing chamber having a diluent inlet, a feed inlet and an outlet, wherein said feed inlet protrudes into said chamber in the fluid path from said diluent inlet to said outlet, and said feed inlet includes a nonreturn valve at the mouth thereof. In such an arrangement the feed inlet is enclosed within the chamber, and is thus protected from external contamination. Furthermore by protruding into the fluid path, the diluent cleans the feed inlet and non-return valve at each dispensing cycle.

The feed material is preferably a liquid drinks concentrate and the diluent is water. The feed inlet preferably comprises an insertable nozzle having an abutment to determine the depth of insertion thereof into said flushing chamber. In a preferred embodiment said nozzle includes a seal for the adjacent inner side of said chamber, so as to prevent fluid in said chamber from passing proximally of the protruding nozzle portion.

In a preferred embodiment the removable nozzle is attached to a closed volume of concentrate, for example a container of liquid drinks concentrate. Typically the nozzle comprises a rigid tubular component hermetically sealed to a flexible delivery line of the container. A container, delivery line and nozzle can be conveniently formed of plastics material and assembled by welding; the container is preferably collapsible so as to be disposable upon removal of the nozzle from the mixing chamber.

Preferably the mixing chamber is incorporated in dispensing apparatus having a feed injector, a diluent injector and a timer whereby the feed injector allows the feed material to pass into the chamber substantially before all diluent has passed through the chamber.

For example the feed material may enter the chamber in advance of the diluent, or during the passage of an initial volume of diluent, for example around 25% or more of the total diluent volume. Up to 85% of the diluent may pass through the chamber during the entry of the feed material. A minimum volume of diluent should pass after termination of entry of feed material, for example 10-25%, preferably 15-20%.

In this way flushing of the feed inlet can be assured. Empirical tests can determine the necessary proportion of diluent which follows entry of the feed material, and the rate of flow of diluent. Dilution of feedstock may be in the range 1 :5 to 1 :50 with respect to diluent.

The feed injector may comprise a peristaltic pump operable to pass a fixed volume of feedstock per cycle. Feedstock is typically supplied to the pump under gravity. An alternative feedstock injector may comprise a solenoid operated valve which is opened for a time period sufficient to dispense the required volume.

The feed injector is preferably adapted to pulse feedstock into the mixing chamber, and may comprise a device responsive to a cyclical electrical signal defining 'flow' and 'no flow' operational states.

Preferably the cylindrical electrical signal is a wave, for example a square wave having high and low values corresponding to 'flow' and 'no flow' states of said device. Alternatively the cyclical electrical signal may be sinuous and repeatedly cross a threshold defining the boundary between 'flow' and 'no flow' states. The wave may be sinusoidal.

The wave may define unequal 'flow' and 'no flow' states in any convenient manner, so as to permit any proportion of 'flow' and 'no flow' periods, from no flow to continues flow.

Preferably a control device is included whereby the 'flow' and 'no flow' periods may be adjusted so as to achieve the desired proportion of feedstock and diluent. In a preferred embodiment feedstock is pulsed into said chamber in more than 5, preferably more than 10, successive pulses, and in the preferred embodiment all said pulses are of equal duration.

The diluent injector may be a peristaltic pump, but is more preferably a solenoid- operated valve adapted to admit a pre-determined volume under mains pressure.

In one embodiment, the mixing chamber comprises an elongate manifold having a plurality of dispensing nozzles protruding through the side wall thereof orthogonally to the elongate axis, the diluent inlet being at one end and the outlet being at the other end. The nozzles may be aligned in the elongate direction, or may be spaced about the periphery of the chamber.

Preferably the chamber further includes means adapted to promote turbulence of diluent in the region of the feed inlet(s), so as to ensure effective cleansing thereof. Suitable turbulence inducing nozzles may be provided at the feed inlets, and assist in flushing sticky or agglomerated feed material.

The invention is particularly applicable to multiple flavour dispensers, where the flushing arrangement repeatedly cleans all nozzles thus avoiding cross-contamination of successive dispensing cycles.

The invention further comprises a method of mixing fluid materials in a chamber having a diluent inlet, and outlet for mixed fluid, and a feedstock inlet, the method comprising the steps of: passing diluent through said diluent inlet, passing material through said feedstock inlet, and terminating the passage of material through the feedstock inlet substantially before terminating the passage of diluent through the diluent inlet, so as to flush said chamber of said material.

Preferably the terminating step allows subsequent passage of up to 25% of diluent. In one embodiment 85% of diluent passes through said diluent inlet prior to terminating passage of feedstock.

In another aspect the invention provides a method of determining exhaustion of feedstock at said feedstock inlet, and comprising the steps of measuring the volume of diluent at said diluent inlet, measuring the volume of feedstock passing through said feedstock inlet, measuring the volume of material passing through said outlet, and determining if the volume of material passing through said outlet is less than the sum of diluent and feedstock. In a preferred embodiment, liquid volume flow meters are provided for the diluent inlet and the outlet.

Preferably this method includes apparatus for measuring volume having an accuracy of better than 0.5%, most preferably better than 0.1%.

Any suitable liquid flow meter may be utilized in a drinks dispenser, and the volume determining device may for example by a means of summing successive angular movements of a peristaltic pump having a predetermined displacement volume per revolution.

In another aspect of the invention there is provided a removable nozzle for insertion into a mixing chamber, and comprising a tubular member having an inlet at one end, an outlet at the other end, a non-return valve at the mouth of said outlet, an external fluid sealing surface proximal of said mouth, and an external abutment proximal of said sealing surface whereby said nozzle is insertable through a wall, the insertion depth being determined by said abutment and an outer wall surface of a mixing chamber, and said sealing surface being immediately adjacent an inner wall surface of said mixing chamber.

The sealing surface is preferably annular and adapted for co-operation with an elastomeric O-ring. Preferably an O-ring is provided on said surface. Most preferably said surface is defined by a circular groove of said tubular member.

The mouth of said tubular member, being distal of said sealing surface, protrudes into the mixing chamber in use, and can be flushed by diluent passing through the mixing chamber. In a preferred embodiment the one-way valve comprises a movable valve member in co-operation with a relatively fixed sealing surface of the tubular member, the movable valve member protruding distally of the mouth of the tubular member, and the sealing surface being immediately proximal of said mouth. BRIEF DESCRIPTION OF DRAWINGS

Other features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only in the accompanying drawings in which :-

Fig. 1 illustrates somewhat schematically a dispensing arrangement incorporating the invention.

Fig. 2 illustrates in perspective view a schematic three nozzle chamber prior to assembly.

Fig. 3 illustrates the chamber of Fig. 2 after assembly.

Fig. 4 illustrates a nozzle for use with the chamber of Figs. 1-3.

DESCRIPTION OF PREFERRED EMBODIMENT

With reference to Fig. 1 a dispensing device includes three containers 10 of concentrate, and a mixing chamber 11 having an inlet 12 connected to a water source via a valve (not shown), and an outlet 13. Water flow is represented by line 14.

Each container 10 feeds by gravity to a respective peristaltic pump 15, from which a predetermined volume of concentrate can be dispensed into the mixing chamber 10 via a respective supply passage 16.

A typical arrangement of mixing chamber is illustrated in Figs. 2 and 3 and comprises an elongate manifold 21 having a circular passage 22 formed along the axis thereof from inlet 12 to outlet 13. Three transverse ducts 23 lead from one side of the manifold 21 to intersect with the passage 22. More or less transverse passages may be provided, as desired.

Fluid supply passages 16 from each container of concentrate terminate in a non-return valve 24, shown schematically. The end of each such passage is a push fit in the respective duct 23 so as to be fluid tight. The passages 16 may for example be constituted by silicone tube 25, and the valves 24 may be a push-fit in the open end. Alternatively the valves 24 may be welded to individual supply tubes, and thus give an absolute hermetic seal.

Each tube 25 is arranged to project into the passage 22 by a predetermined amount, and a respective external collar of the tubes may limit insertion thereof.

In use water passing from the inlet 12 to outlet 13 sweeps over the projecting end, ensuring that concentrate is flushed through the outlet, and that the projecting end is cleaned.

A feature of the invention is that all projecting ends are cleaned regardless of which concentrate is supplied to the chamber 11. Thus cleaning is not dependant on use of any particular supply passage, and all projecting ends are cleaned at least as often as they are used.

Fig. 4 illustrates in greater detail a supply nozzle 31 comprising a hard plastics tubular body 32, e.g. of HDPE or polypropylene, having a serpentine form at the inlet end 33 to receive silicone tubing (not shown). At the outlet end a nozzle 34 includes a nonreturn valve having a valve member 35 which is displaced from a seat at a pre-set upstream pressure.

External sealing rings 36 and an external shoulder 37 provide that the nozzle may be pushed into a manifold 21 and sealed at a pre-determined insertion depth. As illustrated the shoulder 37 contacts the outside wall 28 of the manifold 21, and a sealing ring 36 seals the manifold wall just inboard of the inner wall 29 of the manifold 21. A second proximal sealing ring 36 may be provided, but it not essential.

Preferably the concentrate, typically in the form of a syrup, is metered into the passage 22 via the non-return valve 24 and subsequently flushed by a pre-determined volume of water into a dispensing outlet. The non-return valve(s) seal tightly, thus preventing contamination of the upstream side supply duct. All protruding surfaces in the passage 22 are flushed at each dispensing cycle.

In the alternative, the concentrate may enter the passage 22 as water is flowing, to the intent that all residues are flushed during the dispensing cycle.

In a typical installation, flow rates for both syrup concentrate and water are 2000 ml/min. The internal volume of the mixing chamber is 25 ml. Syrup and water enter the chamber in a combined first phase of 1.5 seconds, following by a flushing period for water only, of 5 seconds. The volume of drink dispensed is about 200 ml.

Plainly the relative volumes depend on the dilution rate required, and the volume per cycle is dependent upon the users requirements. Mixing of concentrate and water may continue in the downstream supply passage, and may be promoted by suitable stirring apparatus.

For convenience in a drinks dispenser, the concentrate may be provided as a disposable, preferably collapsible, bag container having a delivery tube pre-attached with nozzle and one-way valve.

Although this invention has been described in relation to drinks dispensers, the invention is applicable to other kinds of fluid mixing in which two substances require to be combined in pre-determined volume fractions. More than one dispensing nozzle may be used for each dispensing cycle, and the volume dispensed through such nozzles may be different. Furthermore, the dilution rate may be varied either by changing the volume dispensed via the nozzle, or by changing the volume of diluent.