GB2368577A

GB2368577A - A dispenser for draught beverages which simulates a manual beer pump

Info

Publication number: GB2368577A
Application number: GB0117131A
Authority: GB
Inventors: Trevor Hicks
Original assignee: ENGLAND WORTHSIDE Ltd
Current assignee: ENGLAND WORTHSIDE Ltd
Priority date: 2000-07-13
Filing date: 2001-07-13
Publication date: 2002-05-08
Also published as: GB0117131D0; GB0017207D0

Abstract

Dispensing apparatus for draught beverages such as beers and ales comprises a drink inlet (31, fig.3), a drink outlet (32, fig.3), and a valve (35, fig.3) disposed between the inlet and the outlet to control flow between them. The valve (35, fig.3) is controlled by hydraulic or pneumatic pressure, which is generated by a manually operated means. This generation means is adapted to be received in the housing of a manually operated pump 1. The manually operated pressure generating means is preferably a piston 5 including a rod 4 which is attached to a hand-operated lever (50, fig.4). The piston 5 may comprise a plunger which divides the housing into upper and lower chambers 1a, 1b. Moving the piston 5 up and down by means of the lever (50, fig.4) generates changes in pressure in the upper and/or lower chambers 1a, 1b, which operate the opening and closing of the valve (35, fig.3), providing intermittent flow of fluid to the dispense outlet (32, fig.3).

Description

DISPENSING APPARATUS The present invention relates to a dispensing apparatus for dispensing draught alcoholic drinks, such as beer and the like.

Two types of dispensing apparatus are commonly used in public houses (pubs) to dispense draught alcoholic drinks.

The first type of apparatus is a mechanical hand-operated pump (hand pump). The hand pump comprises a pump mechanism operated by a lever that extends vertically from a bar surface. The pump mechanism comprises a piston which draws beer into a housing, and then expels the beer from the housing to beer outlet. An operator of the hand pump pulls the lever, thereby actuating the pump mechanism which draws beer from a barrel. The term cask ale is often used to refer to beer which is stored within a cask and is not pressurised. Cask ale is conventionally dispensed using a hand pump.

A disadvantage of the hand pump is that it is not ideally suited to dispensing beer from a pressurised system, because it can cause gas to break out from the beer (this is known as fobbing).

The second type of known beer dispensing apparatus is designed to dispense beer which is delivered to a dispensing point under pressure. Apparatus of this type typically comprises a valve which is moveable from an off position to an on position to allow beer to flow through the valve. No pumping mechanism is required since the beer is delivered to the dispensing apparatus under pressure.

It will be appreciated that, from the perspective of a customer in a pub, the action of delivering beer from a valve dispensing apparatus has a different appearance when compared to the action of dispensing beer using a hand pump.

There is a long standing requirement in the brewing and public house industry to provide a beer dispensing apparatus which is capable of delivering beer from a pressurised system and which gives the appearance of being a hand pump. Several beer dispensing apparatus have been proposed which convert movement of a lever of a hand pump, via a mechanical linkage, to actuation of a valve. These apparatus suffer from several disadvantages. In particular, the mechanical linkages are susceptible to clogging and jamming caused by beer residue which will over time accumulate upon the linkages. Furthermore, the apparatus in general suffer from the disadvantage that motion of the lever is not translated into smooth and gradual operation of the valve. Instead, the valve is moved rapidly from a closed position to an open position, providing a flow of beer which is either'on'or'off, and does not give the appearance of a mechanical hand pump.

British Patent Application No. 2164921 describes a beer dispensing apparatus in which movement of a lever of a conventional hand pump actuates a piston which, via the transmission of hydraulic pressure, operates a valve which is moved from a closed position to an open position in which beer is dispensed. The apparatus described in GB 2164921 suffers from the disadvantage that it is complicated, and therefore expensive. Furthermore, the apparatus includes several exposed components upon which beer residue will accumulate, and which would be difficult to clean effectively.

The apparatus suffers from the further disadvantage that it cannot be easily retro-fitted to an existing hand pump.

It is an object of the present invention to provide a dispensing apparatus which overcomes or substantially mitigates at least some of the above disadvantages.

According to the invention there is provided a dispensing apparatus for dispensing draught alcoholic drinks, comprising a drink inlet, a drink outlet, and a valve disposed between the drink inlet and drink outlet arranged to control flow of drink between the drink inlet and drink outlet, the valve being controlled via the transmission of hydraulic or pneumatic pressure generated by a manually operated hydraulic or pneumatic pressure generation means, wherein the hydraulic or pneumatic pressure generation means is adapted to be received within a housing of a mechanical handoperated drink pump. The term mechanical hand-operated pump is intended to refer to a pump mechanism operated by a lever that extends from a bar surface, the pump mechanism comprising a piston which draws beer or the like into a housing, and then expels the beer from the housing to a beer outlet. It is this housing within which the hydraulic or pneumatic pressure generation means according to the invention is adapted to be located. The invention is advantageous because it can be easily and cheaply retro-fitted to an existing mechanical hand-operated pump.

Although the invention is particularly suited to retro-fitting to an existing mechanical hand-operated pump, it will be appreciated that it is not essential that the invention be retro-fitted. In particular, although the hydraulic pressure generation means is adapted to be received within a housing of a mechanical hand-operated beer pump, the hydraulic pressure generation means may be provided within a new housing having dimensions similar to that of a housing of a mechanical hand-operated beer pump.

Suitably, the hydraulic or pneumatic pressure generation means is a manually operated piston.

Suitably, a rod which is attached via a mechanical linkage to a hand-operated lever.

Suitably, the piston comprises a plunger having a diameter which corresponds to the inner diameter of the housing, the plunger thereby dividing a chamber formed by the housing into upper and lower chambers.

Suitably, the plunger is provided with valve means operative to allow easy flow of fluid through the plunger when the plunger moves in a downward direction, and to allow restricted flow of fluid through the plunger when the plunger moves in an upward direction.

Suitably, valve means comprises a moveable stopper located in a cavity within the plunger, the cavity being in fluid communication with the upper and lower chambers.

Suitably, the moveable stopper has a lower surface which is engaged by fluid and pushed upwards when the plunger moves in the downward direction.

Suitably, the plunger is provided with one or more holes which allow the restricted flow of fluid through the plunger when the plunger moves in an upward direction.

Suitably, only one hole is provided.

Suitably, the total surface area of the hole or holes is less than 5mm2.

Suitably, the total surface area of the hole or holes is less than 3mm2.

Suitably, the total surface area of the hole or holes is less than 2. 5mm2.

Suitably, the drink control valve is provided in a block, the block being fixed to the housing. The term block is not intended to be limited to a cuboid shape, but instead refers to any suitable shape within which the drink inlet and the drink outlet may be provided.

Suitably, the drink control valve is a moveable stopper located in a channel which connects the drink inlet and the drink outlet.

Suitably, the channel is a bore.

Suitably, the moveable stopper is resiliently biased to an'off position in which drink is prevented from flowing from the drink inlet to the drink outlet. Suitably, the moveable stopper is connected to a diaphragm, the diaphragm having a first surface which is in fluid communication with the lower chamber formed by the housing, and a second surface to which a constant pressure is applied.

Suitably, the first surface forms a lower surface of a diaphragm chamber which is connected via one or more bores to the chamber formed by the housing.

Suitably, movement of the stopper is limited by a surface against which the stopper abuts when in an open position.

Suitably, a head of the piston is held within a chamber defined by a body adapted to be received within the housing.

Suitably, the body is provided with sealing means to seal the body against an inner surface of the housing.

Suitably, the moveable stopper comprises a pair of stopping members spaced apart to allow drink to flow there between when the moveable stopper is moved to an'on' position.

Suitably, hydraulic fluid communication between the valve and the hydraulic or pneumatic pressure generation means is provided via a passage in an upper surface of the housing.

Suitably, the passage is that passage which would have functioned as a drink outlet if the housing were to be used as part of a conventional hand-operated drink pump.

A specific embodiment of the invention will now be described by way of example only, with reference to the accompany figures in which: Figure 1 is a cross-section of a dispensing apparatus according to the invention; Figure 2 is a cross-section of part of the dispensing apparatus illustrated in Figure 1; Figure 3 is a cross-section of a second part of the dispensing apparatus illustrated in Figure 1 ; Figure 4 is a cross-section of an actuating lever of the dispensing apparatus; Figure 5 is a cross-section of a second dispensing apparatus according to the invention; Figure 6 is a cross-section of part of the dispensing apparatus illustrated in Figure 5; and Figure 7 is a cross-section of a known mechanical dispensing apparatus.

Referring to figure 1, a first embodiment of the invention comprises a dispensing apparatus having a housing 1 which defines a chamber. The chamber is provided with an opening 2 at an upper end, and is closed at a lower end by a block 3 containing a valve.

A rod 4 passes through the opening 2 and is connected to a plunger 5. An upper end of the rod 4 is connected via a linkage to a pivotally mounted actuating lever (not shown) which extends substantially vertically from a bar surface. The rod is moved upwards and downward by pulling and releasing the actuating lever.

The plunger is shown in more detail in figure 2. Referring to figure 2, the diameter of the plunger 5 corresponds to the inner diameter of the housing 1, so that the plunger is in contact with the housing 1. A polytetrafluoroethene wiper seal 6a and an 0-ring 6b are located within a circular recess 7 in the plunger 5. The 0-ring 6b acts as a pressure ring which pushes the wiper seal 6a against the housing 1, thereby ensuring that a seal is maintained between the plunger 5 and the housing 1. The plunger 5 effectively separates the chamber into an upper chamber la located above the plunger, and a lower chamber lb located below the plunger.

A valve is provided in the interior of the plunger 5. The valve comprises a moveable stopper 9 formed as a disc and stem which is moveably mounted in a cavity 10 provided in the stopper 5. The cavity 10 is separated by a plate 11 into an upper cavity lOa and a lower cavity

lOb. The plate 11 is provided with holes 12 which allow fluid communication between the lower and upper cavities 10a, lOb. The stopper 9 is mounted in the plate 11, and is resiliently biased in a downward direction by a helical spring 13 which bears against a washer 14 provided at a lower end of the stopper.

The upper cavity 10a has an inner wall 15 which tapers outwardly from the plate 11.

The taper is arranged such that the stopper 9 engages with the inner wall 15, thereby

substantially closing the cavity 10. An 0-ring 16 is provided in a groove 17 around the stopper, to ensure that a seal is made between the stopper 9 and the inner wall 15.

Part of the upper surface of the plunger 5 is cut away to provide an opening 18 which allows fluid communication between the cavity 10 and the upper chamber la.

A bore 20 is provided in the disc part of the stopper 9, and allows a limited amount of fluid communication between the upper and lower cavities lOa, lOb when the stopper 9 is sealed against the inner wall 15 of the upper cavity lofa.

The chamber 1 is filled with water, saline solution, or some other suitable fluid (the

fluid may be a gas). In operation, during upward motion of the plunger 5, the stopper 9 is seated against the inner wall 15 of the plunger 5 and provides a seal between the stopper and the plunger. A small amount of fluid flows from the upper chamber la through the opening 18, the bore 20 and the holes 12 to the lower chamber lb. Since the flow of fluid is restricted by the bore 20, during upward motion of the plunger 5 the pressure in the lower chamber lb decreases, and the pressure in the upper chamber la increases. When upward motion of the plunger 5 ceases, fluid continues to flow through the bore 20 until the pressure in the upper and lower chambers la, lob is equalised.

During downward motion of the plunger 5, fluid in the lower chamber la passes through the holes 12 and presses against the under surface of the disk part of the stopper 9. This pressure overcomes the bias provided by the helical spring 13, moving the stopper 9 upwards and thereby breaking the seal between the stopper and the cavity wall 15. Fluid flows freely from the lower chamber lb through the holes 12, around the stopper 9 and through the opening 18 to the upper chamber la. This flow of fluid equalises pressure in the upper and lower chambers 1 a, lb.

Referring to figure 2, the block 3 will now be described in detail. The block 3 comprises a cylindrical block having a beer inlet bore 31, a beer outlet bore 32, and a central bore 33 which connects the inlet and outlet bores 31,32. A valve comprises a cylindrical stopper 35 which is located in the central bore 33 and is dimensioned so as to close the central bore 33 when in a lowermost position. An uppermost end of the central bore 33 is flared outwardly, and is provided with an 0-ring 36 held in a circular recess 37. An upper end of the cylindrical stopper 35 is provided with a corresponding outward flare, which seals against the 0-ring 36 when the cylindrical stopper is in a lowermost position.

A lower end of the valve block 3 is provided with a recess 37 which, together with an end cap 38 forms a chamber 39. A rubber diaphragm 40 extends across the chamber 39, separating the chamber 39 into two chambers hereafter referred to as the upper diaphragm chamber 39a and the lower diaphragm chamber 39b.

The rubber diaphragm 40 is braced by a pair of plates 41. A lower end of the cylindrical stopper 35 is fixed to the plates 41 and diaphragm 40. A helical spring 42 bears against the plates 41, resiliently biasing the cylindrical stopper 35 in a downwards direction. A lip seal 43 ensures that a seal is maintained against the cylindrical stopper 35 during movement of the cylindrical stopper.

A series of bores 44 pass vertically through the valve block 3, and provide fluid communication between the lower chamber lb and the upper diaphragm chamber 39a.

In operation, during downward motion of the plunger 5, the pressure in the upper and lower chambers la, Ibis equalised. No pressure is generated in the upper diaphragm chamber 39a. The cylindrical stopper 35 remains in its downwards position, sealing the central bore 33 and preventing the flow of beer from the inlet bore 31 to the outlet bore 32.

During upward motion of the plunger 5 the pressure in the lower portion of the chamber 1 b decreases, and this deceased pressure is communicated via the bores 44 to the upper diaphragm chamber 39a. The pressure in the upper diaphragm chamber 39a is then less than the pressure in the lower diaphragm chamber 39b. When this difference in pressure exceeds the force applied by the spring 42, the diaphragm 40 will move upwards, pushing the cylindrical stopper 35 upwards and opening the central bore 33. This allows beer to flow from the beer inlet bore 31 via the central bore 33 to the beer outlet bore 32.

Upwards movement of the cylindrical stopper 35 is limited by a lowermost surface of a central plug 45. Once the cylindrical stopper 35 has reached its uppermost position, the rate of flow of beer to the outlet bore 32 is at a maximum.

The cylindrical stopper 35 moves to the closed position when upward motion of the plunger 5 ceases, since the diaphragm 40 can only maintain the cylindrical stopper 35 in the open position when the pressure in the upper diaphragm chamber 39a is sufficiently low. This means that the cylindrical stopper 35 and diaphragm 40 act in the same manner as a conventional stop valve, i. e. preventing beer from continuing to flow from the apparatus after upward motion of the plunger 5 has ceased.

It will be appreciated that the housing 1 comprises a conventional housing of a conventional mechanical hand-operated pump (hand pump). Thus, an existing hand pump may be easily converted to an apparatus according to the invention by replacing the conventional plunger with the plunger shown in figure 1, sealing a conventional beer outlet provided at an upper end of the housing 1, and fitting a block 3 to a lowermost end of the housing 1.

The size of the hole 20 is very important, and is selected such that operation of the apparatus mimics that of a conventional hand pump. From an operator's point of view, and from a customer's point of view, operation of the apparatus should look and feel similar to that of a conventional hand pump. In particular, the force needed to be applied to an actuating lever in order to cause beer to flow from the outlet bore should be similar to the force used to operate a conventional hand pump.

It has been found that a single hole 20 should be used, typically of 1.7 mm diameter (i. e. 2. 3mm2). A single hole is used in preference to two or more holes having a total surface area of 2.3 mm2, since these holes would have significantly lesser diameters, and may become blocked by particles in the fluid.

The size of the hole should be balanced against the mechanical advantage provided by the actuating lever mounted on the bar surface. The mechanical advantage of such a lever is illustrated in figure 4. Figure 4 shows an actuating lever 50 mounted on a bar surface 51. The lever 50 is connected to a plate 52 at a point A. The plate 52 pivots about a pivot axis B. A lower end of the plate is pivotally connected at point C to a rod 4 via a linkage 53 (the rod 4 corresponds to the rod shown in figure 1). Pulling the lever 50 will, via pivot axis B, move the rod 4 upwards.

The mechanical advantage provided by the lever 50 and plate 52 is determined by the length of the lever, the distance between point A and pivot axis B, and the distance between pivot axis B and point C. In practice, the length of the lever 50 does not vary significantly (typically 15 inches), and it is variation of the distance between A, B and C which leads to differences of mechanical advantage. The hole diameter of 1.7mm (shown in figure 2) is used for the lever 50 and plate 52 shown in figure 4. The tolerance of the hole size should be less than O. lmm, preferably substantially less. If the distance between A and B or between B and C were to be increased, then the hole diameter should be reduced accordingly. Similarly, if the distance between A and B or between B and C were to be reduced, then the hole diameter should be increased accordingly. In general the hole should have a surface area in the range of 0. 5mm2 and 5mm2. The strength of the spring 42 (shown in figure 3) may be altered to change the characteristics of the dispensing apparatus, as described further below. Referring to figure 1 and figure 4, if the hole 20 were to be too small then an overly restricted flow of fluid from the upper chamber la to the lower chamber lb would result. This would make the lever 50 difficult to pull. If the hole 20 were to be too big then the flow of fluid from the upper chamber la to the lower chamber lb would occur too easily, and this would make the lever 50 too easy to pull (i. e. the lever would feel too loose). If the hole 20 were to be too big, then the lever 50 would need to be moved overly quickly in order to ensure that the pressure in the upper diaphragm chamber 39a remained sufficiently low to keep the cylindrical stopper 35 in the open position. The stopper 35 would not remain open for long since the plunger will quickly move to the top of the chamber la, and this would mean that many cycles of the plunger 5 would be required in order to fill a conventional pint glass.

The strength of the spring 42 is selected such that upward motion of the plunger 5 at a desired speed will overcome the downward bias of the spring, and will thereby move the cylindrical stopper 35 upwards to the open position. If the spring is too strong then the pressure drop generated by upward motion of the plunger 5 will not be sufficient to move the cylindrical stopper 35. If the spring is too weak then the cylindrical stopper 35 may move to the open position too easily. In the illustrated embodiment of the invention the spring is characterised in that a pressure of 11 pounds is required to compress the spring by 1 inch. The spring is 0.65 inches long in its relaxed state, and had an outer diameter of 0.66 inches. Other suitable springs may be used.

It will be appreciated that the diameter of the hole 20 and the strength of the spring 42 are to some extent interdependent. It has been found that a single strength of spring may be used, with adjustments of the diameter of the hole 20 used to optimise operation of the apparatus.

When the apparatus shown in figures I to 4 is fitted, the pressure of beer delivered to the apparatus is adjusted so that the rate of flow of beer from the apparatus is optimum when the cylindrical stopper 35 is in the open position. The apparatus is advantageous because its operation is very similar to a conventional mechanical hand-operated pump (hand pump). An operator used to operating a hand pump will find the apparatus easy to use, and a customer will receive beer which appears to have been pumped by a hand pump.

A further advantage of the apparatus of the invention is that beer is not held in the chamber 1, as is the case with a hand pump. Beer may be held in the chamber of a hand pump for some considerable time, and may warm to the ambient temperature.

Since the volume of the chamber is considerable, the warm beer will form a significant fraction of a pint of beer dispensed from the hand pump, and the temperature of the pint of beer will be too close to room temperature. The apparatus of the invention does not hold beer in the chamber 1, thereby overcoming this problem.

A second embodiment of the invention is illustrated in figures 5 and 6. Referring to figure 6, a dispensing apparatus comprises a hollow cylindrical body 101 provided with an opening 102 at a upper end, and closed by a cap 103 at a lower end.

The cylindrical housing 101 and cap 103 comprise part of a conventional mechanical hand-operated pump (hand pump). In a conventional hand pump, a pump mechanism (not shown) extends across the inner diameter of the cylinder 101, and actuation of the pump mechanism draws beer in through an inlet 104 provided in the cap 103 and out through an outlet 105 provided at the upper end of the cylinder 101.

The beer dispensing apparatus according to the invention does not draw beer through the inlet 104, and the inlet 104 is closed with a screw-plug 106.

The cylinder 101, which is hereafter referred to as the outer cylinder 101, contains a second hollow cylinder 107, hereafter referred to as the inner cylinder 107. An upper end of the inner cylinder 107 is provided with a collar 108 which is dimensioned to fit against an inner surface of the outer cylinder 101. Two 0-rings 109 extend around the circumference of the collar 108 and provide a seal between the collar 108 and the outer cylinder 101. The inner cylinder 107 defines a chamber 110 comprising a main part having a constant diameter over the majority of the length of the inner cylinder 107, and a lesser part with a lesser diameter at a lowermost end of the inner cylinder 107. The chamber 110 tapers to a narrow bore 111 at a base of the inner cylinder 107. The narrow bore 111 provides a degree of fluid communication between the chamber 110 and the interior of the outer cylinder 101 (the inner cylinder 107 is not sealed against the cap 103).

A piston 112 is located within the chamber 110 of the inner cylinder 107. The piston is provided with a rod 113 which extends vertically through the opening 102 at the upper end of the outer cylinder 101. An upper end of the rod 113 is connected to a manually operated lever (not shown). The connection between the rod 113 and the manually operated lever is configured in the manner of a conventional hand pump. A channel 114 connects the chamber 110 of the inner cylinder 107 to the outlet 105.

Referring to figure 6, a housing 115 is fixed to an upper surface of the outer cylinder 101. The housing 115 comprises a block which is provided with a beer inlet bore 116 and a beer outlet bore 117. A vertically disposed connecting bore 118 connects the beer inlet bore 116 and the beer outlet bore 117. The housing 115 includes a cylindrical protrusion 119 which provides an extension of the connecting bore 118.

The housing 115 is securely fixed to the outer cylinder 101, for example using bolts (not shown). The housing 115 is positioned such that the cylindrical protrusion 119 is located within the outlet 105 of the outer cylinder 101.

A valve is provided within the connecting bore 118. The valve is a moveable stopper 120 which comprises two solid cylinders 121 connected by a rod 122 which extends between the cylinders (the stopper is formed from a single piece of plastics). The stopper 120 is dimensioned to fit closely within the connecting bore 118. A pair of 0rings 123 is located at either end of the stopper 120, to provide a seal between the stopper 120 and the connecting bore 118. The stopper 120 is moveable between a lower'off position in which flow of beer from the beer inlet bore 116 to the beer outlet bore 117 is prevented, to an upper'on' position in which flow of beer from the beer inlet bore 116 to the outlet 117 is allowed. The beer flows around the rod 122 of the stopper 120. The stopper 120 is biased towards the lower'off position by a helical spring 124.

Referring to figures 5 and 6, in use the outer cylinder 101 and inner cylinder 107 contain water at atmospheric pressure. Beer is delivered to the beer inlet bore 116 at pressure, for example around 40 pounds per square inch (psi). When the manually actuated lever (not shown) is in an upright position, the piston 120 is located at or close to the bottom of the main part of the chamber 110, and the stopper 120 is biased to the lower'off position by the helical spring 124. When the manually actuated lever is moved away from the upright position, this movement is translated into upward motion of the piston 112. The upward motion of the piston 112 compresses the air held above the piston 112 in the chamber 110, increasing the air pressure within the chamber 110. The increased air pressure is transmitted via the outlet 105 to the connecting bore 118, and gradually pushes the stopper 120 upwards against the force of the helical spring 124, thereby moving the stopper 120 towards the upper'on' position. The movement of the stopper 120 from the'off position to the'on'open position is gradual and is controlled by movement of the manually actuated lever.

During upward movement of the piston 112, air flows into the chamber 110 through the narrow bore 111. This prevents a vacuum from building up beneath the piston 112.

During downward motion of the piston 112, the pressure of the water above the piston 112 is gradually reduced, and the stopper 120 gradually returns to the lower'off position.

The invention is advantageous because it provides delivery of pressurised beer in a flow which is controlled by movement of a manually operated lever. This allows pressurised beer, for example keg beer, to be delivered in a manner which has the appearance of the delivery of cask ale via a conventional hand pump.

A further advantage of the invention is that the apparatus is easily cleaned as its internal workings are contained within appropriate housings.

A further advantage of the invention is that it may be retro-fitted easily to a conventional hand pump. A conventional hand pump is illustrated in figure 107.

Common components are given the same reference numerals as those used in relation to figures 1 and 2. The conventional hand pump comprises a cylinder 11, a cap 103, a pumping mechanism 130, a rod 103 and a water-cooled jacket 129.

The invention may be retro-fitted to the conventional hand pump as follows. The cap 103 is removed from the cylinder 101, and the pumping mechanism 130 and rod 130 are removed. Referring to figure 5 and figure 7 the inner cylinder 107 and replacement piston 120 are fitted into the cylinder 101. The rod 130 of the piston 120 is connected to a manually actuated lever 131 of the hand pump in a conventional manner using an existing linkage 132. A beer inlet channel 104 of the cap 103 is closed using a rubber bung 105, and the cap 103 is replaced over the cylinder 101. A beer delivery spout 133 is removed from the cylinder 101. Referring to figure 5 and figure 7, the housing 150 is fixed to the cylinder 101, and the beer delivery spout 133 (or a replacement beer delivery spout disposed at a different angle) is inserted into the beer outlet bore 170 of the housing 150. An 0-ring seal 135 is located between the beer delivery spout 133 and the housing 150. A beer inlet tube (not shown) is connected to the inlet bore 160 of the housing 150.

Several parts of the conventional hand pump are retained when the invention is retrofitted. Retro-fitting of the invention may be carried out quickly and easily.

The outer cylinder 101 and inner cylinder 107 may contain any fluid suitable for the transmission of hydraulic or pneumatic pressure, for example nitrogen gas or water. Although the illustrated embodiment of the invention is retro-fitted to an existing mechanical hand-operated pump, it will be appreciated that it is not essential that the invention be retro-fitted. In particular, the apparatus illustrated in figures 1 and 2 may be fabricated from new, and sold and/or fitted as a single entity.

Claims

Claims 1. A dispensing apparatus for dispensing draught alcoholic beverages, comprising a drink inlet, a drink outlet, and a drink control valve disposed between the drink inlet and drink outlet arranged to control flow of drink between the drink inlet and drink outlet, the drink control valve being controlled via the transmission of hydraulic or pneumatic pressure generated by a manually operated hydraulic or pneumatic pressure generation means, wherein the hydraulic or pneumatic pressure generation means is adapted to be received within a housing of a mechanical handoperated pump.
2. A dispensing apparatus according to claim 1, wherein the hydraulic or pneumatic pressure generation means is a manually operated piston.
3. A dispensing apparatus according to claim 2, wherein the piston includes a rod which is attached via a mechanical linkage to a hand-operated lever.
4. A dispensing apparatus according to claim 2 or claim 3, wherein the piston comprises a plunger having a diameter which corresponds to the inner diameter of the housing, the plunger thereby dividing a chamber formed by the housing into upper and lower chambers.
5. A dispensing apparatus according to claim 4, wherein the plunger is provided with valve means operative to allow easy flow of fluid through the plunger when the plunger moves in a downward direction, and to allow restricted flow of fluid through the plunger when the plunger moves in an upward direction.
6. A dispensing apparatus according to claim 5, wherein valve means comprises a moveable stopper located in a cavity within the plunger, the cavity being in fluid communication with the upper and lower chambers.
7. A dispensing apparatus according to claim 6, wherein the moveable stopper has a lower surface which is engaged by fluid and pushed upwards when the plunger moves in the downward direction.
8. A dispensing apparatus according to any of claims 5 to 7, wherein the plunger is provided with one or more holes which allow the restricted flow of fluid through the plunger when the plunger moves in an upward direction.
9. A dispensing apparatus according to claim 8, wherein only one hole is provided.
10. A dispensing apparatus according to claim 8 or claim 9, wherein the total

2 surface area of the hole or holes is less than 5mm2.
11. A dispensing apparatus according to claim 10, wherein the total surface area 2 of the hole or holes is less than 3mm.
12. A dispensing apparatus according to claim 10, wherein the total surface area 2 of the hole or holes is less than 2. 5mm2.
13. A dispensing apparatus according to any preceding claim, wherein the drink control valve is provided in a block, the block being fixed to the housing.
14. A dispensing apparatus according to any preceding claim, wherein the drink control valve is a moveable stopper located in a channel which connects the drink inlet and the drink outlet.
15. A dispensing apparatus according to claim 14, wherein the channel is a bore.
16. A dispensing apparatus according to claim 14 or claim 15, wherein the moveable stopper is resiliently biased to an'off position in which drink is prevented from flowing from the drink inlet to the drink outlet.
17. A dispensing apparatus according to any of claims 14 to 16, wherein the moveable stopper is connected to a diaphragm, the diaphragm having a first surface which is in fluid communication with the lower chamber formed by the housing, and a second surface to which a constant pressure is applied.
18. A dispensing apparatus according to claim 17, wherein the first surface forms a lower surface of a diaphragm chamber which is connected via one or more bores to the chamber formed by the housing.
19. A dispensing apparatus according to any of claims 14 to 18, wherein movement of the stopper is limited by a surface against which the stopper abuts when in an open position.
20. A dispensing apparatus according to claim 2 or claim 3, wherein a head of the piston is held within a chamber defined by a body adapted to be received within the housing.
21. A dispensing apparatus according to claim 20, wherein the body is provided with sealing means to seal the body against an inner surface of the housing.
22. A dispensing apparatus according to any of claims 13 to 16, wherein the moveable stopper comprises a pair of stopping members spaced apart to allow drink to flow there between when the moveable stopper is moved to an'on'position.
23. A dispensing apparatus according to any of claims 1 to 3,13 to 16 or 20 to 22, wherein hydraulic fluid communication between the valve and the hydraulic or pneumatic pressure generation means is provided via a passage in an upper surface of the housing.
24. A dispensing apparatus according to claim 23, wherein the passage is that passage which would have functioned as a drink outlet if the housing were to be used as part of a conventional hand-operated drink pump.
25. A dispensing apparatus substantially as hereinbefore described with reference to the accompanying figures.