GB2084546A - Liquid metering apparatus - Google Patents

Abstract

For enhancing the accuracy in the volumetric metering of beer, a flow meter (10) which is provided in the dispense line emits a pulse each time a predetermined volume of beer passes therethrough. After dispensing, for example, a half pint of beer the number of pulses received by an intermediate store (12) are compared by a digital comparator (14) with a corresponding number of pulses in a permanent store (16) corresponding to an exact half pint measure. If the registered pulses from the store (12) are within a range of 10% less or more than the number of pulses in the store (16) a computer (18) varies the number of registered pulses to equal the number of nominal pulses and the varied number of pulses is then entered into a totalisator (20). By means of the rounding up or down feature, the inherent inaccuracy in the flow meter becomes of little significance in terms of overall accuracy. <IMAGE>

Description

SPECIFICATION Method and apparatus for metering the flow of a fluid This invention relates to a method of and apparatus for metering the flow of a fluid and is particularly concerned with the volumetric metering of beer.

In premises where beer is dispensed, for stock control and other purposes, there is a requirement for a system which will meter the quantity of liquid dispensed, and such a system contains either an integral recording device or a flow transducer which passes signals to a remote totalising and recording unit. Where beer is dispensed by a free flow system, a flow meter is often used to measure the volume of beer dispensed, but a major disadvantage of such a system is the inherent inaccuracy of many basic forms of flow meters which are used, such as turbine, pelton wheel, manometer and other types. Taking into account the variations which occur in the free flow dispense of beer, such as speed, pressure, topping up, under or over measure, a conventional flow measurement system is not able to record quantities of beer dispensed with any degree of accuracy.Even when costly, instrumentation standard flow meters are used, such factors as acceleration, over-run and degradation of performance during life result in poor system accuracy.

It has been attempted previously to design a more accurate flow meter but without much success, and therefore it is an object of the present invention to improve the overall accuracy of a metering arrangement while enabling the use of conventional equipment such as flow meters.

According to the present invention there is provided a method of metering the flow of a fluid, said method comprising the steps of providing signals representative of a flow of predetermined volumes of the fluid past a metering position, registering the number of signals provided within a period during which the fluid is dispensed, comparing the number of registered signals with a nominal number of signals, and, when the number of compared registered signals is within a predetermined range, varying the number of registered signals for totalising.

Preferably the predetermined range is between 10% less or more than the nominal number.

Preferably also the method provides for sensing a predetermined period during which no flow occurs before comparing the number of registered signals with the nominal number.

According to the present invention there is also provided apparatus for metering the flow of a fluid, said apparatus comprising metering means adapted to provide signals representative of the flow of predetermined volumes of the fluid past a metering position, means for registering the number of signals provided within a period during which the fluid is dispensed, means for comparing the number of registered signals with a nominal number of signals, means for varying the number of registered signals, and means for recording the number of registered signals for totalising.

Preferably means are provided for sensing a predetermined period during which no flow occurs.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a graph illustrating the method of recording registered signals; Fig. 2 is a graph illustrating a typical timing sequence; and Fig. 3 is a block diagram showing a circuit arrangement.

To comply with generally accepted principles in clubs, and legislation in public houses, beer is usually dispensed by volumetric meter, or in the case of free flow dispense, into lined or brim measure glasses. The accuracy therefore is to a large extent built into the method of dispense in multiples of half pints.

Referring to the drawings, a flow meter 10 is provided in the dispense line and is adapted to emit a pulse each time a predetermined volume of beer passes therethrough. The pulses emitted by the flow meter 10 are received in an interrilediate store 1 2. After dispensing of, for example, a half pint, the stored number of pulses are compared by a digital comparator 14 with a corresponding number of pulses known to correspond to an exact half pint measure and previously stored in a permanent store 1 6. Because of the inherent inaccuracy of the flow meter, the number of pulses registered in the store 12 may not correspond to the number of pulses in the store 1 6, but if the registered pulses from the store 12 are within a range of 10% less or more than the number of pulses in the store 16, then a computer 1 8 will vary the number of registered pulses to equal the number of nominal pulses in the store 16, and this varied number of pulses will be entered into a totalisator 20.

Because "topping up" of beer takes place at the end of a dispense, and also because in busy periods it is not practical to carry out the comparison and enter a signal in the totalisator 20 each time dispensing is terminated, timing circuitry including an envelope detector 22 and a re-triggerable timer 24 are used to sense a nominal pause, for example 2 seconds, after dispensing has terminated and only if that pause is sensed will comparison and entry into the totalisator 20 take place. The intermediate store 12 enables the registering of pulses representing multiples of half pint volume so as to accommodate periods where several dispense periods take place before the nominal pause is available.Also the comparator 1 6 is provided with a pluraiity of window circuits so as to compare with different nominal numbers of pulses representative of multiples of half pint volumes.

As shown in Fig. 1, when the registered signals are compared and occur within the range of 10% less or more than the nominal number of pulses, the registered pulses are varied in number before being entered into the totalisator 20. If the number of pulses is outside such a range, then a signal representing the actual registered number is entered into the totalisator 20. It will be appreciated that, although the inherent inaccuracy of the flow meter will still be apparent when the registered number of signals occurs outside the range, for example when beer is mixed with other liquids, the proportion of such drinks in relation to beer only is not great and the inaccuracy is of little significance in terms of overall accuracy.

In a licensing period in which, for example, 90% of dispenses are discrete half pints or pints, and 10% are quarter pint shandies, the flow meter provides a volume measurement inaccuracy of, say, + 5% for each dispense during this period. By means of the rounding up or down feature the + 5% inaccuracy is converted to 100% accuracy for 90% of the transactions, and this is entered into the totalisator. The remaining 10% of transactions not recognised as half pint dispenses are entered into the totalisator exactly as received, with + 5% inaccuracy. As 90% of transactions entered into the totalisator now have 100% accuracy and only 10% of the transactions are + 5% inaccurate, then the overall system inaccuracy is + 0.5%.

Conversely, the system accuracy is 99.5%.

The circuitry receiving the pulses from the flow meter, together with the computer and the totalisator, are housed in a central unit which may be common to a number of dispense outlets. One system consists of one central processor unit (C.P.U.), up to thirty two flow meters and a printer unit. The system operates continuously with the C.P.U. scanning round the thirty two flow meters to sense when flow is taking place. When flow is taking place, the C.P.U. logs the amount of beer dispensed through each outlet, and adds each dispense onto the total for that outlet. By this method there is always in the memory of the C.P.U. a running total of how much beer has been dispensed by each outlet. Upon command, the C.P.U. will print out the contents of its memory, therefore giving a record of how much beer has been dispensed since the memory was last cleared.The operation of the printer does not clear the memory. If desired, the memories may be cleared by the operation of a separate key controlled switch. The C.P.U. always prints out the contents of the memories before clearing them.

The C.P.U. records not only the amount of liquid dispensed by each outlet, but also the status of each outlet. This status may beL a) flow meter operational, b) no flow meter has ever been connected, c) a flow meter has been connected but is now disconnected, or d) a flow meter is now connected and has been disconnected (n) times.

In addition to recording the status of each flow meter, as described above. the C.P.U. also records the number of times the mains has been disconnected. During mains disconnection, the content of the memories is not lost, but the C.P.U.

cannot monitor new sales. An integral stand-by power supply may be incorporated.

On receipt of a print command (i.e. the pressing of the print button on the C.P.U.) the C.P.U. prints out the following: 1) A heading stating what the printout is; 2) The amount of beer dispensed by outlet 1, and the status of outlet 1; 3) The amount of beer dispensed by outlet 2, and the status of outlet 2; 4) As above for outlets 3 to 32; and 5) The number of times the power has been disconnected. When a 'clear' request is made (i.e.

the 'clear' button on the front panel is pressed) then the C.P.U. prints as above then clears all memories.

Because of the versatility which is designed into the C.P.U., a control computer may be connected in place of the printer. This control computer then has the authority to 'talk' to the C.P.U., and to override the front panel controls of the C.P.U. (i.e. 'Print' and 'Clear'). When the control computer wishes, data is transmitted from the C.P.U. memory to the control computer.

Facilities also exist for the C.P.U. to be connected via a telephone link to a remote computer, for example at head office. The C.P.U. is designed to readily interface with a stock control system which will monitor sales from spirit measures and metered beer outlets.

By virtue of the described metering system the overall accuracy of totalising or monitoring the quantities of beer dispensed is increased, whilst the inherent inaccuracy of the flow meter is tolerated.

Claims (11)

1. A method of metering the flow of a fluid, said method comprising the steps of providing signals representative of the flow of predetermined volumes of the fluid past a metering position, registering the number of signals provided within a period during which the fluid is dispensed, comparing the number of registered signals with a nominal number of signals, and, when a number of compared registered signals is within a predetermined range, varying the number of registered signals to the nominal number before recording the number of registered signals for totalising.

2. A method according to claim 1, wherein the predetermined range is between 10% less or more than the nominal number.

3. A method according to claim 1 or 2, wherein the nominal number of signals is representative of a half pint volume of the fluid.

4. A method according to any of claims 1 to 3, including providing different nominal numbers representative of multiples of half pint volumes of the fluid, and sensing a predetermined period during which no flow occurs before comparing the number of registered signals with a respective one of the nominal numbers.

5. Apparatus for metering the flow of a fluid, said apparatus comprising metering means adapted to provide signals representative of the flow of predetermined volumes of the fluid past a metering position, means for registering the number of signals provided within a period during which the fluid is dispensed, means for comparing the number of registered signals with a nominal number of signals, means for varying the number of registered signals, and means for recording the number of registered signals for totalising.

6. Apparatus according to claim 5, wherein the comparison means comprises a digital comparator which compares the number of signals from an intermediate store with the number of signals in a permanent store.

7. Apparatus according to claim 5 or 6, wherein the means for varying the number of registered signals comprises a computer.

8. Apparatus according to any of claims 5 to 7, wherein means are provided for sensing a predetermined period during which no flow occurs.

9. Apparatus according to claim 8, wherein the sensing means comprises timing circuitry including an envelope detector and a retriggerable timer.

10. A method of metering the flow of a fluid substantially as hereinbefore described with reference to the accompanying drawings.

11. Apparatus for metering the flow of a fluid substantially as hereinbefore described with reference to the accompanying drawings.