GB2444979A - A frozen beverage machine including peltier plates - Google Patents

Abstract

A frozen beverage machine (10) includes a chamber (11), a scraper blade (12) and a series of Peltier plates (14) mounted closely adjacent a wall (13) of the chamber. The frozen beverage machine is preferably operable in a continuous "on demand" mode by virtue of a dispensing tap (37) and generally of a much smaller scale than existing "slush" machines.

Description

A FROZEN BEVERAGE MACHINE

The present invention relates to a frozen beverage machine of the type that produces a slush" beverage of fine ice for drinking.

Slush machines of various types are known, usually for dispensing a beverage product with ice in a crushed form fine enough to drink from a glass/cup or with a spoon. Such machines usually incorporate a reservoir of s2gnificant capacity (at least several litres) and a conventional refrigeration apparatus.

Large machines use a cooled glycol solution in a heat exchange arrangement. A batch of premixed beverage is maintained in a cylindrical chamber about which is located a sleeve through which the cooled glycol passes. Ice crystals form on the surface of the chamber and a scraper rotating within the chamber slowly turns to dislodge the crystals formed. It will be appreciated that in these large machines it can take considerable time (many hours) before a slush beverage is ready to be dispensed. Furthermore, due to the high capacity of the machine, significant waste can occur when it is time to be emptied and cleaned.

For applications when a high volume (large machine) is not practical and particularly in a bar where a premium alcoholic product is require to be dispensed, a more compact frozen beverage machine is required, to minimise waste but deliver a comparable or superior product to existing slush machines.

In one broad aspect of the present invention there is provided a frozen beverage machine including a chamber, a moving means within said chamber, and a Peltier plate mounted closeJy adjacent a wall of the chamber.

Preferably the Peltier plate arrangement will be a plurality of plates with matched thickness, sandwiched between two discs.

Matched thickness ensures that the plates are most efficient in heat transfer to the discs. Preferably the discs are made from aluminium.

In a preferred embodiment of the present invention the chamber is a cylinder, most preferably a shallow cylinder with a diameter substantially greater than its height, thereby maximising cooling surface to volume ratio. In a preferred form of this embodiment the Peltier plate or plurality of plates are mounted to both ends of the cylindrical chamber.

Preferably the moving means is a rotatably mounted scraper/wiper at a central axis of the cylinder with a blade that wipes an end wall or both end walls of the chamber. The wiper blades are designed to wipe the surface of the plates to loosen the ice crystals forming thereon. Blades are shaped to prevent the compaction of ice crystals normally associated with scraping.

Preferably the blades also have features (such as fins on the back) that create turbulence and prevent localised compaction.

The combined motion of the blade and rotor arm carries ice crystals around and maintains them in suspension. As the ice volume increases this motion slows considerably but still maintains a homogenous mix. Preferably the blade has a shallow angle to prevent it just moving the whole of the slush around the chamber. A flat-faced blade would tend to move the slush as one piece.

Preferably the frozen beverage machine includes a heat exchange means (e.g. apparatus containing a flowing cooling fluid) adjacent a hot side of the Peltier plate. A "cooling gallery" heat exchanger can utilise a water source from the bar or public nouse where the apparatus is installed.

In a preferred form the chamber includes an inlet for beverage thereinto and outlet coupled to a dispenser tap.

Preferably the product infeed is temperature controlled (e.g. with a heater cartridge around the inlet) to prevent thermal sink back from the chamber to the product line, thereby preventing the input from freezing when there is no demand for product (i.e. idling). Preferably the shape of the inlet is designed to disperse incoming liquid so that you do not get a "channel" of liquid from the inlet within the slush.

The present invention is configured for precise control of product temperature to ensure quality and consistency. Since the incoming liquid is at a higher temperature than the solution in the chamber, temperature sensors (e.g. at least three) are arranged so they read a mixture of incoming product and slush.

In this way a signal to energise the Peltier plates is provided until a set point is reached. It should also be noted that power to the Peltier plates is preferably ramped up and down (as opposed to sudden on/off switching) to minimise thermal shock on the plates that might crack them or cause a semi-conductor break down.

The frozen beverage machine according to the oresent invention will be described by reference to the accompanying drawings, wherein: -Figure 1 shows a simple schematic view of a frozen beverage machine according to the present invention, Figure 2 shows an exploded component view of a frozen beverage machine according to a further embodiment of the present invention, and Figure 3 shows a view of the wiper blade.

A simpU.fied etibodiment of the present invention is illustrated by Figure 1. A frozen beverage machine 10 is comprised of a shallow cylindrical chamber 11 within which rotates a scraper blade 12 closely adjacent to at least one wall 13 (that wall being circular if viewed in plan). Embedded or otherwise mounted with the wall 13 is a series of Peltier plates 14 with a wire 15 connecting same to an electrical source (not shown) Adjacent Peltier plates 14 a channel 16 is provided for heat exchange purposes. Generally a fluid would enter at inlet 17 and leave at exit 18, drawing heat away from the "hot side" of Peltier plates 14 once energised. Other forms of heat exchanger, heat sink (usually a metal construction with fins that uses its thermal mass to draw heat away from a hot object) or even a fan-cooled construction could be used in the present invention, depending on design requirements.

Beverage product enters and leaves chamber 11 by virtue of product infeed 19 and dispense end 20 respectively. Dispense end 20 would most likely be connected with a dispenser tap or similar with a closure that delivers product on demand.

The advantage of the present invention in the preferred form is that the unit can be scaled down to a bar-top type apparatus by virtue of the use of Peitier plates for refrigeration. Peltier plates are known for use on small scale apparatus such as CPU cooling in computer technology, but not commonly used in the beverage industry.

A detailed theory of Peltier devices will not be explained in the present description, however, a summary is as follows: Peltier devices, also known as thermoelectric (TE) modules, are small solid-state devices that function as heat pumps. A "typical" unit is a few millimetres thick and up to several centimetres square. It is a sandwich formed by two ceramic plates with an array of small Bismuth Telluride cubes ("couples") in between. When a DC current is applied heat is moved from one side of the device to the other -where it must be removed by a heatsink. As such Peltier plates have "hot side" and a "cold side". In the present case the cold side is obviously located adjacent wall 13 of chamber 11 to cool the contents therein.

Peltier plates can be clustered or even stacked to achieve lower temperatures. Although not considered the most energy efficient cooling method, any disadvantage is offset by the advantages of no moving parts, no hydrocarbon refrigerant, no noise, no vibration, small size, long life and accurate temperature control.

For the required aPplication in the present invention, the cluster of Peltier plates have a closely matched thickness such that when they are sandwiched and bonded between two aluminium discs (chamber plate 31 and cooling plate 28 in Figure 2) they are most efficient in use.

As illustrated, Peltier plates 14 are provided at a flat circle-shaped wall 13 of cylindrical chamber 11 to cool liquid (beverage) therewithin. In fact, ice crystals form on wall 13 inside the chamber relatively quickly after Peltier plates 14 are energised. In order to ensure that a thick layer of ice cannot form a low adhesion surface can be provided on wall 13 and, to "mix" ice into the bulk of the beverage, a moving means in the form of scraper 12 wipes away ice crystals as it rotates by virtue of motor 21.

Since chamber 11 is a shallow cylinder, the dimensions of scraper 12 preferably fit within its diameter to rotate and ensure that ice is cleared from a substantive surface of circular wall 13.

In a preferred form of the invention the frozen beverage machine operates continuously, that is, as slush iced beverage is dispensed from end 20 (via a tap or similar), more beverage is piped through product infeed 19 at pressure. However, Peltier plates 14 may not be permanently energised in use. Accurate temperature control enables the power to be ramped up and down as necessary. Furthermore, designing the unit with sufficient thermal insulation can maintain the beverage in a slush form for better energy efficiency.

It should further be noted that, on start up, it is possible to observe super-cooling. In other words product reaches a temperature where ice crystals spontaneously form throughout the product without necessarily being created on the plates. This effect occurs when product is uniformly cooled to a particular temperature. In this context the super-cooling effect is desirable as it quickly forms the slush allowing power to the Peltier plates to be reduced.

The shallow nature of chamber 11 is intended to provide only a small volume (say two servings worth of beverage) that will cool/freeze to the desired level in a small amount of time, e.g. 2 minutes.

A test apparatus made according to the invention with a 1.7 L chamber (i.e. much more than two servings) takes approximately minutes to be ready to serve slush product. Such a chamber would have a diameter approximately 25 to 30 cm and height of 6 to 8 cm) . Large slush machines with much greater dimensions may take an hour or more to reach a state where servings can be made.

Higher power (and faster heat exchange) to the Peltier plates 14 results in a proportional decrease in the time taken to cool a given volume. Also, a proportional increase in scraper rotation Mternatively, in Figure 2, a frozen beverage machine according to the present invention can utilise two banks of Peltier plates 14 at both ends of cylindrical chamber 11, providing faster freeze processing of the beverage. A thermocouple 22 provides temperature data to a control circuit that calculates required power to the Peltier plates 14 and scraper motor. Three or more temperature sensors can provide more accurate control on larger volumes and aid the quality and volume of ice crystals.

The sandwich construction of machine 10 is seen clearly from the exploded view of Figure 2. All components are clamped together between two support frames 23 by virtue of tie bars 24. This provides structural integrity to operate at elevated internal pressures.

Components visible 1r Figure 2 include: Coolant manifold 25 -a circular disc with a maze of turbulence producing channels 16 formed on the surface to direct a coolant fluid between an inlet 26 and outlet 27. In the preferred embodiment the coolant is water, readily available to be plumbed into the machine in a bar type environment. Other fluids such as glycol could also be used as a coolant. This feature has become known as a "cooling gallery".

Cooling plate 28 -a thin aluminium disc sealing by virtue of o-ring 29 against manifold 25 to keep it watertight.

Peltier location plate 30 -in direct contact with cooling plate/manifold 25 such that heat from the hot side of Peltier plates 14 is drawn away. Peltier plates 14 slot in or are otherwise clipped into location plate 30 which is sized in a conforming disc shape. Peltier plates 14 themselves are generally supplied as square tiles. Alternative arrangements of the ?eltier device may be/become available.

Chamber plate 31, another aluminium disc, is in direct contact with the cold side of the Peltier device and sealed by an o-ring 32 against housing 33.

Housing 33 contains chamber 11 which, as described above, is a shallow cylindrical bore closed at both ends by chamber plates 31.

Scraper 12 is mounted for rotation on a shaft 34 that extends tnrouch an aperture in all the above disc shaped components and connected to a motor (not illustrated in Figure 2) Furthermore, each of the two blades of scraper 12 is in contact with a chamber plate 31 so that both opposing cooling surfaces are being scraped (or more particularly, wiped) to remove ice simultaneously. A detailed view of the blade is provided by Figure 3 wherein two opposed wedge-shaped rubber blades l2a are mounted to contact each of the chamber plates 31. In use the blades move in the direction of arrow S. The shallow angle of a blade 12a ensures that it displaces the slush and does not merely move it as one piece. It further has the effect of lifting ice crystals formed from the Peltier plates into the middle section of the chamber. Fins 12b on the trailing side of blade l2a create turbulence to prevent localised compaction.

The motion of the blades maintains the ice crystals in suspension, as the ice volume increases this motion slows considerably but still maintains a homogenous mix.

A dispensing means 35 is installed in housing 33, comprised of a bore (nor. visible) in communication with chamber 11 into which is inserted a screw feeder 36 that, in use, urges crushed beverage toward a dispenser tap 37. Screw feeder 36 can be electrically or manually activated and also serves as an additional crushing step before beverage is finally delivered to the customer. A screw feed (auger) is not a mandatory component but may be necessary dependent on the viscosity (i.e. percentage content of ice crystals) Beverage is fed into housing/chamber 11 via a product infeed aperture 20 in an accessible side of the housing 33.

As mentioned above, it is important that the Peltier plates 14 between the cold side plate 31 and the hot side plate 28 (known as the "cooling plate" because it cools the hot side of the Peltier plate) are the same thickness and good contact is maintained with both plates to facilitate efficient heat transfer.

Preferably, a matera1 or compound is used to help facilitate heat transfer between the Peltier plates and plates 28 and 31.

Such a material may be a graphite polymer coated aluminium foil (commercially available as Qpad2Th from Bergquiste (3K Ltd) Alternatively, a heat conductive gel can be used in the Peltier/plate sandwich to account for any minor inconsistencies ri thickness. Many other coupling agents may be substituted for the foil and gel examples described.

s illustrated in Figure 2, the components each side of housing 33 are mirrored such that there is a second set of Peltier plates, cooling plate, manifold etc. The frozen beverage machine of the present invention can be manufactured by available materials and techniques.

Modifications may be made for economy and aesthetics as it is intended that the unit could be installed in a bar environment or even in a domestic dwelling.

The invention is most suited to making slush from an alcoholic base beverages, however, non-alcoholic beverages with an adequate sugar content would also work.

The preferred form of the invention features a cylindrical chamber with the Peltier device(s) at each end thereof, however, future embodiments could allow for Peltier devices to be arranged around the side walls of a cylindrical chamber. Also other chamber shapes are equally possible (such as a square with a reciprocating wiper blade spanning thereacross)

II

Component llst by reference to Figure 2: Frozen beverage machine 11 Chamber 12 Scraper blade 14 Peltier plates 16 Heat exchange channels 19 Product infeed 22 Thermocouple 23 Support Frames 24 Tie Rods Coolant manifold 26 Coolant inlet 27 Coolant outlet 28 Cooling plate 29 0-ring Peltier location plate 31 Chamber plate 32 0-ring 33 Housing 34 Scraper shaft Dispensing means 36 Screw feeder 37 Dispenser tap

Claims (14)

1. WHAT WE CLAIM IS: 1. A frozen beverage machine including a chamber, a

   moving means within said chamber, and a Peltier plate mounted closely adjacent a wall of the chamber.
2. 2. The frozen beverage machine of claim 1 wherein the chamber is shallow with a diameter/width greater than its depth.
3. 3. The frozen beverage machine of claim 1 or 2 wherein there are a plurality of Peltier plates of matched thickness.
4. 4. The frozen beverage machine of claim 1, 2 or 3 wherein the Peltier plate is mounted adjacent a flat end of the chamber.
5. 5. The frozen beverage machine of any of the preceding claims wherein the moving means includes a wiper blade mounted for movement within the chamber adjacent the Peltier plate.
6. 6. The Frozen beverage machine of claim 5 wherein a leading edge of the blade is angled (relative to its contact with the chamber) and a trailing edge includes fins.
7. 7. The frozen beverage machine of any one of the preceding claims including a heat exchange means adjacent a hot side of the Peltier plate.
8. 8. The frozen beverage machine of claim 7 wherein the heat exchange means is a water cooled channel, a heat 5ink, or a fan. I.,
9. 9. The frozen beverage machine of any one of the preceding claims further including an inlet and outlet for beverage into/out of the chamber.
10. 10. The frozen beverage machine of claim 9 wherein the outlet includes a dispenser tap.
11. 11. The frozen beverage machine of claim 9 or 10 able to operate continuously.
12. 12. The frozen beverage machine of claim 4 wherein there are a plurality of Peltier plates mounted adjacent two flat ends of the chamber and the moving means includes a scraper blade mounted adjacent or to contact each flat end.
13. 13. The frozen beverage machine of any one of the preceding claims further including temperature sensing and control means to manage electrical power to the Peltier plate and a motor associated with the moving means.
14. 14. The frozen beverage machine substantially as herein described with reference to the accompanying drawings.