Prepayment water supply systems

Abstract: A prepayment water supply system comprises a prepayment unit having a receptacle for receiving a prepayment token in the form of a key, and a solenoid-operated valve controlled by the prepayment unit for controlling the water supply. The key has a memory containing credit and identification data, and the prepayment unit closes the valve when the credit represented by the credit data is exhausted. However, a bypass passage is provided which permits a supply of water at a relatively low flow rate when the valve is closed, so that enough water for drinking and filling lavatory cisterns (albeit very slowly) continues to be supplied.

Description: This invention relates to prepayment water supply systems, and is more particularly but not exclusively concerned with prepayment water supply systems based upon the prepayment systems disclosed in our United Kingdom Patents Nos. 2 153 573 and 2 191 622. The prepayment systems described in our United Kingdom Patent Nos 2 153 573 and 2 191 622 allow access to a metered commodity, and comprise a prepayment token in the form of key having a memory, a receptacle for the key (the receptacle typically forming part of a meter arranged to meter the commodity), and a circuit (also typically forming part of the meter) for allowing access to the commodity only when authorised by predetermined data read from the key memory. The data in the key memory is typically entered into the memory by inserting the key into a receptacle in a vending machine, typically located at the commodity supplier's premises, the machine then entering the data in return for payment, eg via a coin or bank note accepting unit forming part of the machine. The data typically includes credit data representative of the monetary amount paid, and data representative of tariff information and one or more unique identification codes. In use, the circuit in the meter reads the data from the key, and permits the supply of the commodity to continue until the credit represented by the credit data is exhausted, at which point it discontinues the supply. It is an object of the present invention to render the systems of the preceding paragraph particularly suitable for use as prepayment water supply systems. According to the present invention, there is provided a prepayment water supply system comprising a prepayment token having a memory, and supply control means including an electrically-operable valve for controlling the supply of the water, a receptacle for receiving the token, a circuit coupled to the receptacle and to the valve and responsive to credit data read from the token memory to close the valve when an amount of water or a time period determined by said credit data has been supplied or has elapsed, and a bypass passage which permits the supply of water at a relatively low flow rate when the valve is closed. The relatively low flow rate, typically a few litres per hour, is chosen to be sufficient to meet basic health requirements, ie to provide drinking water and to enable lavatory cisterns to fill (albeit very slowly), but sufficiently low to provide a strong incentive to the consumer to purchase more credit. The bypass passage may be formed in the valve itself, for example in the valve body or in the valve closure member, or it may be separate from the valve and arranged to bypass the valve altogether. In this latter case, the bypass passage may additionally bypass the metering unit as well. The supply control means may also include a metering unit for metering the water, in which case the circuit may include fraud indicator means for producing and storing a fraud indicating signal if the metering unit senses flow when the valve is closed, the fraud indicator means being responsive only to flow rates in excess of said relatively low flow rate if the bypass passage does not bypass the metering unit. The invention will now be described, by way of example only, with reference to the accompanying drawing, which is a simplified block diagram of a prepayment water metering system in accordance with the present invention; The prepayment water metering system shown in the drawing is intended for installation in a water consumer's premises, and is closely based on the system described in our United Kingdom Patent No. 2 191 622 (which was in turn a development of the system described in our United Kingdom Patent No. 2 153 573). Thus the system comprises a key 10, known as a customer key, containing a non-volatile memory such as an EEPROM, and a prepayment unit 12 having a receptacle 14 for receiving the key 10. The physical form of the key 10 and the receptacle 14 can be as described in our United Kingdom Patent No. 2 191 883. Associated with the receptacle 14, within the unit 12, is a key interface circuit 16 coupled to a microprocessor 18. The microprocessor 18 is coupled in turn to another non-volatile memory 20 in the form of an EEPROM, to a clock 22 and to a display 23, all forming part of the unit 12. The microprocessor 18 is also coupled to a flow meter 24 connected in the main water inlet pipe 26 to the consumer's premises, and to a solenoid-operated valve 28 also connected in the pipe 26. The meter 24 and the valve 28 are preferably mounted in a common housing (not shown), and are connected to the unit 12 via an electrical cable. The system operates substantially as described in our United Kingdom Patents Nos. 2 153 573 and 2 191 622. In particular, the consumer takes the key 10 to a vending machine, typically located in or at a post office or other readily accessible premises, and inserts the key 10 into a receptacle, similar to the receptacle 14, in the machine. The consumer then inserts coins or bank notes into the machine, which, having read the key memory, responds by writing credit data representative of the amount of credit purchased into the key memory, possibly along with tariff data representative of the current water supply tariff or tariffs and pass number data indicative of how many times the key has been used. The key memory typically already contains identification data uniquely identifying the key, the meter or prepayment unit with which it is to be used and the consumer, all of which identification data was entered when the key 10 was first issued to the consumer. Having charged the key 10 with credit, the consumer returns home and inserts the key into the receptacle 14. This causes the microprocessor 18 to read the contents of the key memory, to perform checks to see if these contents indicate a valid key as described in United Kingdom Patent No. 2 153 173, and if they do, to write them into the memory 20. The microprocessor 18 also writes the current reading or readings of the meter 12, which are stored in the memory 20, along with the time and date to which the readings relate, into the key memory, substantially as described in United Kingdom Patent No 2 191 622. The principal difference between the system of the present invention and the system of our earlier United Kingdom Patents Nos. 2 153 573 and 2 191 622 (aside from the storage of monetary credit and tariff information in the key memory rather than an amount of water purchased) lies in what happens when the credit entered into the unit 12 is exhausted. In systems so far manufactured and sold by the Applicant under the aforementioned patents, which systems have primarily been for use in connection with the supply of electricity, the supply of electricity is discontinued when the credit entered into the unit 12 is exhausted (although an emergency supply facility, allowing access to a predetermined amount of electricity or providing a predetermined amount of credit, is always incorporated). However, where the commodity being supplied is water, a complete discontinuance of the supply could perhaps have adverse health implications. In the system of the present invention, therefore, a small by-pass conduit 30, capable of permitting a flow of about two litres per hour, is arranged in parallel with the valve 28. This flow is sufficient to provide drinking water and to fill lavatory cisterns (albeit rather slowly), but is nevertheless sufficiently inconvenient as to provide a powerful incentive to the consumer to purchase fresh credit by way of the key 10. It will be appreciated that the flow through the by-pass conduit 30 is metered by the meter 24. Accordingly, if the unit 12 includes fraud detection means of the kind which produces and stores a fraud indication signal if flow is sensed while the value 28 is closed, the fraud detection means should be programmed to ignore flows lower than a certain threshold, selected to be just above the maximum flow which could pass through the by-pass conduit 30. Many modifications can be made to the described embodiment of the invention. For example, the by-pass conduit 30 can be replaced by a conduit formed in the body of the valve 28, or even in the valve closure member of the valve 28. Alternatively, the by-pass conduit 30 can by-pass the meter 24 as well as the valve 28, in which case the aforementioned fraud detection means need not be programmed with a low flow threshold. Additionally, the key 10 need not have the physical form of a key, but can instead be constituted for example by a so-called "smart card" or by a magnetic card. And finally, the water supply can be pre-paid for on a timed basis, rather than on a metered basis (ie a given amount of credit permits supply for say a week or a month). In this case, the metering function can still be retained, with the clock 22 and the microprocessor 18 serving additionally to provide the necessary timing function, and with the meter readings still being entered in the key 10 along with time and date information. However, in the limit, the metering function can be omitted altogether, eg by omitting the flow meter 24. But even in this case, it may still be desired to store information generated in or by the consumer's part of the system in the key 10, eg the aforementioned signal stored in the EEPROM 20 and indicating a possible fraud.

Claims: A prepayment water supply system comprising a prepayment token (10) having a memory, and supply control means (12) including an electrically-operable valve (28) for controlling the supply of the water, a receptacle (14) for receiving the token, a circuit (16, 18) coupled to the receptacle and to the valve and responsive to credit data read from the token memory to close the valve when an amount of water or a time period determined by said credit data has been supplied or has elapsed, and a bypass passage (30) which permits the supply of water at a relatively low flow rate when the valve is closed. A prepayment water supply system as claimed in claim 1, wherein said relatively low flow rate is about two litres per hour. A prepayment water supply system as claimed in claim 1 or claim 2, wherein the bypass passage is formed in the valve itself. A prepayment water supply system as claimed in claim 3, wherein the bypass passage is formed in the valve closure member. A prepayment water supply system as claimed in claim 3, wherein the bypass passage is formed in the valve body. A prepayment water supply system as claimed in claim 1 or claim 2, wherein the bypass passage is separate from, and completely bypasses, the valve. A prepayment water supply system as claimed in claim 6, wherein the supply control means includes a metering unit for metering the water, and the bypass passage additionally bypasses the metering unit as well. A prepayment water supply system as claimed in claim 7, wherein the circuit includes fraud indicator means for producing and storing a fraud indicating signal if the metering unit senses flow when the valve is supposed to be closed. A prepayment water supply system as claimed in any one of claims 1 to 6, wherein the supply control means includes a metering unit (24) for metering the water, and the circuit includes fraud indicator means for producing and storing a fraud indicating signal if the metering unit senses flow when the valve is closed, the fraud indicator means being responsive only to flow rates in excess of said relatively low flow rate.

Inventors: MANWELL JOHN, MANWELL, JOHN
Applicants: SCHLUMBERGER IND LTD, SCHLUMBERGER INDUSTRIES LIMITED
Application year: 1992
Main classification: G07F15
IPC codes: G07F7, G07F15