WO2002001164A1

WO2002001164A1 - Flow meter for liquids

Info

Publication number: WO2002001164A1
Application number: PCT/GB2001/002879
Authority: WO
Inventors: Hassan Talal Yousef Assali; Atef Abdel Salam Abdel-Hady; Yousef Ahmad Osailan
Original assignee: Hassan Talal Yousef Assali; Abdel Hady Atef Abdel Salam; Yousef Ahmad Osailan
Priority date: 2000-06-27
Filing date: 2001-06-27
Publication date: 2002-01-03
Also published as: AU2001266198A1; GB0015535D0

Abstract

There is described a meter for measuring a flow of a liquid, the meter comprising a passage (4) through which the liquid may flow, a rotary element (7) mounted to extend at least partially into said passage (4) so as to be rotatable by the liquid flowing through the passage, electromagnetic sensing means for sensing rotation of the rotary element, determining means for determining a flow rate of liquid through the passage on the basis of the sensed rotation and display means (13) for displaying information related to said determined flow rate. Preferably the passage has an orifice (6) of predetermined size upstream of the rotary element.

Description

Flow meter for liquids.

The present invention concerns flow meters for liquids, and is particularly concerned with a flow meter for measuring water flows in domestic and industrial supply arrangements .

Conventional water meters for determining the consumption of water by a household or user generally comprise a turbine rotated by the water flow, and a mechanical transmission or gear train which drives a mechanical counter from the rotation of the turbine. A drawback with such apparatus is that significant driving force is required from the turbine to operate the mechanical counting arrangements, and at low flow rates the forces generated on the turbine may be insufficient to drive the counting mechanism, leading to errors in the measurement of the volume of water consumed.

The present invention seeks to provide a flow meter for liquids, particularly but not exclusively for use in measuring domestic consumption of water from a mains supply, wherein an accurate measurement of the flow of water can be made even when the flow is small .

A further aspect of the invention is to provide a domestic or industrial water meter which can accurately measure the volume of water consumed by a user, without the need for a complex mechanical counting arrangement and drive transmission.

According to the present invention, there is provided a meter for measuring a flow of a liquid, the meter comprising a passage through which a liquid may flow, a rotary element mounted at least partially in said passage so as to be rotatable by a liquid flowing through the passage, electromagnetic sensing means for sensing rotation of the rotary element, means for determining a flow rate of liquid through the passage on the basis of the sensed rotation, and display means for displaying information related to said determined flow rate.

In a preferred embodiment, the rotary element is a Pelton wheel mounted in a chamber immediately downstream of an orifice through which liquid may pass to impinge sequentially on radially-extending vanes of the Pelton wheel. Most preferably, the orifice is a circular opening and the axis of the Pelton wheel extends substantially tangentially with respect to the orifice.

Preferably the displayed information is a cumulative total volume of liquid which has passed through the passage. Embodiments of the present invention will now be described in detail, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a water meter according to the invention;

Figure 2 is a top view of the water meter shown in Figure i;

Figure 3 is a vertical section of the water meter of Figures 1 and 2;

Figure 4 is a schematic diagram of electronic circuitry of the water meter;

Figure 5 is an illustration of the data stored in a correlation module;

Figure 6 is an illustration of the data stored in a tariff memory table;

Referring now to Figures 1 to 3, the water meter comprises an upper housing part 1 containing the electronic circuitry, and having an upwardly-facing opening 2. The opening 2 is sealed by a transparent cover 3. At the lower part of the meter, a horizontal passage 4 is provided with a threaded connection 5 at each of its ends, for connection to a water pipe. The passage 4 has a coaxial orifice 6 positioned slightly upstream of its midpoint, and immediately downstream of the orifice a Pelton wheel 7 is mounted in an enlarged chamber 8 extending upwardly of the passage, so that water flowing through the orifice 6 will impinge on the lower (as seen in the Figure) vanes 9 of the Pelton wheel 7 to cause the wheel to rotate. The rotation axis of the Pelton wheel 7 is oriented substantially tangentially to the passage 4 and to the orifice 6.

The orifice 6 is preferably circular, and for general domestic use may have a diameter of approximately 7 mm.

This will result in water flowing through the orifice 6 at approximately 40 cm/sec when a flow rate of only 1 litre/min is established through the meter. Even at a small volumetric of flow rate, the considerable flow velocity through the orifice 6 will ensure that the

Pelton wheel 7 is turned and consumption is recorded.

For meters which are expected to handle larger flow rates that are normally encountered in domestic water supply, the orifice 6 may be made larger and the diameter of the Pelton wheel 7 may be increased correspondingly. The vanes 9 of the Pelton wheel 7 are formed from a metallic or a magnetic material, so that rotation of the wheel may be detected by a sensing coil. In the preferred embodiments, the Pelton wheel 7 is an injection-molded component formed from plastics material with a magnetic filler. In the illustrated embodiments, the Pelton wheel 7 has six radially-extending vanes 9, but it is foreseen that any suitable number of vanes may be provided.

The chamber 8 is bounded at its upper face by a top wall 10, to the upper face of which is mounted a sensing coil 11 for detecting rotation of the Pelton wheel 7. The sensing coil 11 is electrically connected to a circuit board 12 mounted in the upper part of the housing 1 , and having a display 13 which is visible through the transparent cover 3 which seals the opening 2 in the^' upper face of the housing 1.

The circuit board 12 comprises a processor 20, a clock circuit 21, memory modules 22 and 23, and the display 13. The elements of the metering circuit are illustrated in figure 4, together with optional elements such as an input/output device 24, a tariff memory table 25, and a transceiver 26. The water meter shown in Figures 1 to 3 is of a simplified type, in which the display 13 indicates only a cumulative total of the volume of water which has passed through the meter. The meter is intended to be read by the water supplier at the end of each billing period, and the consumption of water in the preceding period is calculated from the difference of the last two readings .

The circuitry for this simplified type of meter comprises the sensing coil 11 for generating pulses as water flows through the meter, a processor 20 for performing the data processing, the clock circuit 21 for defining time intervals, a total memory module 22 for storing the cumulative total, a correlation module 23, which is a memory module storing correlations between the number of pulses in a time interval and a corresponding volume of water passing through the meter in that time interval, and a display 13.

In operation, water flowing through the orifice 6 in the passage 4 causes the Pelton wheel 7 to turn, and the repeated passage of the Pelton wheel vanes 9 past the sensor coil 11 causes the coil to generate a series of pulses, each pulse coinciding with the passage of a vane past the coil. The processor 20 operates in a sequence of clock intervals, each interval having a predetermined length. During a clock interval, the processor receives the train of pulses from the sensor coil 11, and counts how many pulses have been received in that clock interval. The processor 20 then "looks up" in the correlation module 23 the value for the volume of water which corresponds to the number of pulses counted, and adds that value to a cumulative total. The total is then stored in the total memory module 22, which is preferably a non-volatile memory, and is also sent to the display 13. The displayed total thus represents the volume of water which has passed through the meter in all preceding time intervals.

The processor counter is then reset, and the number of pulses in the next clock interval is counted. The processor then determines from the correlation module 23 the volume of water passing through the meter in the next clock interval, and adds it to the cumulative total, updating the stored total in the total memory module 22 and the display 13.

The values stored in the correlation module 23, illustrated schematically in figure 6, are determined in a calibration mode for a meter having the same passage 4 and orifice 6 dimensions as the meter in which the circuit board is to be used. In the calibration mode, water is passed through the passage 4 and orifice 6 at a number of predetermined flow rates, and for each flow rate the number of pulses generated by the sensing coil 11 in a predetermined clock interval is recorded. From the flow rate and the length of the clock interval, an increment value corresponding to the volume of water passing through the passage 4 during each clock interval is calculated and recorded, to be associated with the number of pulses counted at that flow rate. The calibration mode may be performed at a number of different pressure ranges, and for a number of different Pelton wheels, so that a plurality of correlation tables are generated, correlating the increment value and number of pulses for each Pelton wheel at each pressure range.

The correlation module 23 may be programmed to store a single correlation table corresponding to the Pelton wheel fitted to the meter and to the water pressure where the meter is to be used. When the correlation module 23 is programmed to store a number of different correlation tables each corresponding to a particular Pelton wheel and a range of mains water pressures, then on installation of the meter the installer will install a particular Pelton wheel, and will test the mains water pressure and then, using an input device, will select the appropriate correlation table to be accessed by the processor.

The clock circuit 21 of the meter may include a real-time clock, which the installer will set to local time during the installation process. Where a real-time clock is available, the meter may include a further memory, the tariff memory table 25, in which the installer may set starting and ending times to define intervals during which different tariffs are payable for the consumption of water. Such a table is shown in schematically in figure 5 , with a first tariff band W extending from 7 a.m. to 10 a.m., a second tariff band X from 10 a.m. to 4 p.m., and so on. The total memory module will then include not only a cumulative total, but also a stored total for the volume of water corresponding to each tariff band.

Where the meter includes the real-time clock and the tariff memory table, the processor 20 will determine as before a volume of water corresponding to a clock interval, and will add that volume to the cumulative total. The processor will also compare the current time with the time intervals set in the tariff memory table, and will add to the stored total for the appropriate tariff band (W, X, etc) an increment corresponding to that volume. The display may display only a single number, corresponding to the cumulative total. Alternatively, an input device may be provided so that the display may sequentially display the cumulative total, and the total for each of the tariff bands. In a further alternative, the display may have a plurality of display fields, so that the cumulative total and the tariff band totals may be displayed simultaneously.

In a further development of the meter circuitry, the correlation module 23 may store a correlation between the number of pulses in a clock interval and an instantaneous flow rate, and the meter may display the instantaneous flow rate as well as or instead of the cumulative total volume. Alternatively, the correlation module may store a correlation between the number of pulses in a clock interval and the volume of water flowing in that interval, and the processor may calculate an instantaneous flow rate from the length of the clock interval and the volume of water flowing in the clock interval.

The meter circuitry may optionally also include a transceiver circuit 26, to allow remote reading of the values stored in the total memory module. The transceiver circuit 26 shown in figure 4 may be a radio transceiver, or alternatively the circuit board may include a modem connection for communication via a telephone line.

The meter circuitry may optionally also include an input/output device 24 such as an RS232 port or other electrical connection accessible via an opening 15 in the housing 1 to enable the meter to be read directly without an operator having to read the display and then enter the totals via a keyboard. The total memory module 22 may also store an identification number unique to the meter, and which is attached to the data read from the total memory. The input/output device 24 may alternatively be a keypad mounted to the housing 1.

The power supply for the electronic circuitry is preferably derived from batteries 14 contained within the housing 1, most preferably attached to the circuit board 12. Where the meter is mounted in an exposed location, rechargeable batteries may be used and solar panels may be provided to charge the batteries during hours of sunshine. In a further alternative embodiment, a secondary turbine may be provided downstream of the Pelton wheel 7 or turbine, the secondary turbine driving an alternator or generator to provide power for the metering circuitry. As an alternative to the Pelton wheel 7 illustrated in figure 1, an axial flow turbine may be mounted in the chamber 8 with its rotation axis substantially parallel to the length of the passage 4 and spaced upwardly from the centerline of the passage, so that water issuing from the orifice 6 will impinge on the lower blades of the turbine and cause it to turn, while the upper blades of the turbine pass close to the sensing coil to provide the sensing input for the processor.

The meter described and illustrated is oriented with its passage 4 horizontal and positional below the housing 1. It is to be understood that the meter may be mounted in any orientation, such as with the passage 4 vertical or inclined, and the housing may be above, below, or to one side of the passage 4.

The Pelton wheel or turbine is preferably manufactured to have a density close to that of water, in order to reduce bearing friction to a minimum. The material for the Pelton wheel or turbine and its bearings is preferably selected so as to be lubricated by water.

While the meter has been described in relation to a domestic water meter, it is to be understood that with suitable selection of materials the meter may be used with other liquids .

Claims

1. A meter for measuring a flow of a liquid, the meter comprising: a passage through which a liquid may flow; a rotary element mounted to extend at least partially into said passage so as to be rotatable by a liquid flowing through the passage: electromagnetic sensing means for sensing rotation of the rotary element: determining means for determining a flow rate of liquid through the passage on the basis of the sensed rotation; and display means for displaying information related to said determined flow rate.

2. A meter according to claim 1, wherein the passage comprises an orifice of predetermined area.

3. A meter according to claim 2, wherein the orifice is a circular opening substantially coaxial with the passage .

4. A meter according to any of claims 1 to 3 , wherein the rotary element is formed from a metallic or a magnetic material .

5. A meter according to any of claims 1 to 4 , wherein the rotary element is formed from a synthetic plastic material with a magnetic filler.

6. A meter according to any preceding claim, wherein the rotary element is mounted in a chamber immediately downstream of an orifice.

7. A meter according to claim 6, wherein the rotary element is a Pelton wheel comprising a number of radially-extending vanes, and is mounted for rotation about an axis extending substantially tangentially with respect to the orifice.

8. A meter according to claim 6 , wherein the rotary element is an axial-flow turbine comprising a number of radially-extending vanes, and is mounted for rotation about an axis extending substantially parallel to the axis of the passage, and spaced therefrom.

9. A meter according to any preceding claim, wherein the electromagnetic sensing means comprises a sensing coil mounted adjacent the chamber and adapted to detect the sequential passage of the vanes of the rotary element and to produce an electrical signal corresponding to the passage of each vane past the sensing coil.

10. A meter according to claim 9, wherein the determining means comprises : means responsive to the electrical signal from the sensing means for counting the number of vanes which pass the sensing coil in a predetermined time interval; first memory means for storing a correlation between the number of vanes which pass the sensing coil in a predetermined time interval and an increment value corresponding to a volume of liquid passing through the passage in said time interval; second memory means for storing a total value corresponding to the total volume of liquid which has passed through the passage; means for retrieving from said first memory means an increment value corresponding to the volume of liquid passing through the passage in said predetermined time interval on the basis of said number of vanes counted; means for adding said increment value to said total value stored in said second memory means; and output means to output a signal to the display means representative of said total value.

11. A meter according to claim 10, wherein said second memory means is adapted to store a plurality of tariff total values, each corresponding to a predetermined tariff period, and the determining means comprises a clock circuit, and wherein the means for adding said increment value adds the increment value to said total value, and to one of said tariff total values on the basis of the output offset clock circuit.

12. A meter according to claim 10 or claim 11, wherein the determining means includes means to calculate an instantaneous flow rate of liquid on the basis of the said increment value, and includes means to provide an output signal to said display means to cause the display means to display said instantaneous flow rate.

13. A meter according to any of claims tended to 12, wherein the meter further comprises a transceiver circuit for receiving and interrogating signal, and for transmitting a signal including data representative of said total value.

14. A meter according to claim 13, wherein the transceiver circuit is adapted to transmit data identifying the meter when transmitting the signal including data representative of said total value.

15. A meter according to any of claims 10 to 14, wherein the meter further comprises input/output means for providing an electronic output representative of said total value.

16. A meter according to claim 15, wherein said input/output means comprises an input/output port.

17. A meter according to claim 15, wherein said input/output means comprises a keypad.