Encoder-type register for an automatic water meter reader

An encoder-type register for an automatic meter reader to be interfaced with a visual read-only register of the kind found in a water meter that measures water consumption. The water meter register has a rotatable sweep hand that carries a magnet and rotates around a register plate in relation to the speed and volume of water moving through the water meter. A plurality of (e.g., three) magnetic (e.g., Hall effect) sensors are fixedly positioned one-after-another in the path of the magnet carried by the rotating sweep hand. The magnetic sensors measure the magnetic field produced by the rotating magnet and generate corresponding output signals. A microprocessor receives the output signals generated by the magnetic sensors whenever the magnet rotates therepast. The microprocessor stores information concerning the number of rotations of the magnet carried by the sweep hand depending upon the direction in which the magnet is being rotated as an indication of water consumption. The microprocessor provides the stored information to a meter interface unit connected to a set of output terminals of the encoder register so that such information can be transmitted from the meter interface unit to a remote data collector over a wireless communication path.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an encoder-type register to be interfaced with a standard visual read-only register of the kind commonly found in a water meter that measures water consumption. By virtue of the encoder-type register of this invention, an indication of water consumption can be automatically recorded and transmitted to a remote data collector for processing (e.g., billing, analysis or record-keeping purposes).

2. Background Art

Residential and commercial structures which receive water from a utility or municipality usually have a water meter connected to the water line to monitor water consumption. Conventional water meters have a visual read-only register which includes a rotating sweep hand that moves in relation to the velocity and amount of water being consumed. A rotating mechanical wheel-type counter is incremented as the sweep hand rotates. The counter provides a numerical indication of water consumed by a user.

In this regard, it is necessary that the counter of the read-only register be read on a regular basis so that the water supplier can bill the user for its consumption. To accomplish the foregoing, a meter reader typically travels from one water meter to the next throughout the day to make a visual inspection of the associated counters and manually record the numerical values indicated thereby. The values collected by the meter reader are carried back to the water supplier for processing. However, such a technique of employing meter readers to personally visit and visually inspect the read-only register of every water meter along his route is time consuming, inefficient, relatively expensive, and may result in inaccurate readings being taken by a tired or inattentive workman.

Therefore, what is desirable is a means by which to automatically obtain an indication of the volume of water flowing through a water meter so that corresponding information can be collected and transmitted to the water supplier without the requirement that a water meter reader personally gain access to and visually inspect the water meters of users.

SUMMARY OF THE INVENTION

In general terms, an encoder-type register for an automatic meter reader is disclosed to be interfaced with a standard visual read-only register commonly found in a conventional water meter that measures water consumption of a user. The visual read-only register includes a numerically inscribed register plate and a rotatable sweep hand which moves around the register plate in relation to the speed and volume of water moving through the water meter. A mechanical wheel-type counter that is visible through the register plate is incremented each time the sweep hand completes a rotation around the register plate so that a numerical value indicative of the user's water consumption can be read from the counter and manually recorded for processing.

The encoder-type register of the automatic meter reader is located in a protective encoder housing that sits atop the water meter. The encoder-type register is adapted to automatically monitor and record the user's water consumption and transmit an indication thereof to a remote data collector without the need for a meter reader to personally visit and visually inspect the read-only register. According to a preferred embodiment, a magnet is affixed to one end of the sweep hand so as to be rotatable therewith around the register plate of the read-only register. A plurality of (e.g., three) magnetic sensors (preferably Hall Effect devices) are positioned in the path of the rotating sweep hand and the magnet carried thereby. A battery-powered microprocessor that is mounted on a circuit board within the encoder housing takes measurements of the magnetic sensors. Signals generated by successive ones of the sequence of magnetic sensors are amplified, digitized and measured by the microprocessor to provide an indication when the sweep hand has completed one revolution around the register plate and that water is flowing in a forward direction through the water meter. Should the microprocessor detect signals generated by the magnetic sensors in an opposite sequence, an indication is provided of water backflow through the water meter and the sweep hand rotating in an opposite direction around the register plate.

The microprocessor has an internal register in which to store a record corresponding to the rotations completed by the sweep hand around the register plate and the magnet moving past the sequence of magnetic sensors. The record (i.e., count) is incremented after each revolution of the sweep hand. The number stored in the register will be decremented in the event that the microprocessor detects water backflow and signals generated by the magnetic sensors in an opposite sequence. Output data is provided by the microprocessor to a set of output terminals by way of conductive pins which run upwardly from the circuit board, through the encoder housing, to an output terminal housing at which a set of wires are connected to respective ones of the output terminals. The wires extend outwardly from the output terminal housing for connection to a commercially-available meter interface unit stationed adjacent the water meter. The meter interface unit is adapted to receive the output data from the microprocessor and transmit the data (e.g., by wireless means) to a remote data collector for processing. The microprocessor is programmed to complete its measurement of the magnetic sensors and transmit the output data at predetermined times as determined by an internal clock or periodically in response to a demand signal initiated by the meter interface unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An encoder-type register1of an automatic meter reader to be interfaced with a standard visual read-only register is disclosed below. By way of example only, the encoder-type register1is ideally suited for use in reading a conventional water meter of the kind used to measure the volume, in cubic feet, of water consumed by a residential or commercial user. A suitable water meter50with which the encoder-type register1of this invention can be incorporated is illustrated inFIGS. 1 and 2of the drawings. In this case, the water meter1includes a visual read-only register having a numerically-inscribed register plate52and a rotatable sweep hand54which moves over and around the register plate52at a speed that is proportional to the velocity and amount of water moving through the body56of water meter50between inlet and outlet ports58and60. A mechanical rotating wheel-type counter62that is visible through an opening in the register plate52is incremented as the sweep hand54completes rotations around the register plate. Counter62can be read by a meter reader so that a numerical value indicative of the user's water consumption can be recorded for processing by the water supplier.

A register cover64is pivotally coupled to a shroud55that sits upon the body56of the water meter50. The register cover64is rotatable from a closed position as shown inFIG. 1, at which to cover the register plate52and the visual read-only counter62, to an open position as shown inFIG. 2, at which the register plate52, sweep hand54and counter62are visually accessible to the meter reader for inspection.

The encoder-type register1of this invention supplements the usual visual read-only register commonly used with water meters and provides an efficient way to automatically read and record the user's water consumption without the requirement that a meter reader personally visit and inspect each water meter of each user. The encoder-type register1is surrounded and protected by an encoder housing3. A battery housing5in which a battery is carried is located at one side of the encoder housing. The encoder housing3is preferably connected to the top of the shroud55of water meter50adjacent the register cover64. An encoder output terminal housing7is mounted atop the encoder housing3. As will be described when referring toFIGS. 4 and 5, a set of (e.g., three) shielded output wires are surrounded by and extend outwardly from the output terminal housing7to be connected to a meter interface unit, the function of which will be disclosed in greater detail hereinafter.

FIG. 3of the drawings represents the register plate52of the read-only register water meter50ofFIGS. 1 and 2. The sweep hand54is coupled to a waterflow-responsive turbine assembly (not shown) positioned between the inlet and outlet ports58and60of water meter50so that the sweep hand is rotated by the turbine assembly around the register plate52. As an important feature of this invention, a series of (e.g., three) magnetic sensors, designated A, B and C, are spaced from one another in the path of the sweep hand54. As is best shown inFIG. 5, the magnetic sensors A, B, and C are located above the register plate52. A (e.g., disc-shaped) magnet8is attached to and carried at one end of the sweep hand54. As the sweep hand54rotates around the register plate52, the magnet8is correspondingly moved past successive ones of the magnetic sensors A, B and C in response to water flowing through the water meter50from the inlet port58thereof to the outlet port60.

Details of the encoder-type register1of this invention including the series of magnets A, B and C past which the magnet8carried by the sweep hand54is moved are now described while referring toFIGS. 4 and 5of the drawings. Positioned within the shroud55above the body56of water meter50is a hollow copper can66which is common to many modern water meters. The register cover64which is pivotally coupled to the shroud55is shown inFIG. 5in the aforementioned open position rotated away from the glass layer68at the top of the can66to permit visual access to the register plate52and the rotatable sweep hand54.

The register plate52and sweep hand54are disposed inside the hollow can56. The magnet8carried by the sweep hand54is mounted within a pocket10at one end of the sweep hand. Located at the top of the can66above the register plate52and the rotatable sweep hand54is a piece of transparent protective (e.g., glass) material68. When the register cover64is rotated relative to the shroud55to the open position (ofFIG. 2) the protective material68prevents a manual or environmental interference with the rotation of the sweep hand54and the magnet8that is carried thereby around the register plate52.

As previously explained while referring toFIG. 3, the magnet8that is carried by the sweep hand54is moved sequentially past a series of magnetic sensors A, B and C. The magnetic sensors A, B and C are mounted below a circuit board12of the encoder-type register1. The circuit board12and the magnetic sensors A, B and C are located in and surrounded by the encoder housing3. The encoder housing3is preferably filled with a non-conductive potting material in which the circuit board12and magnetic sensors are embedded. Also mounted on the circuit board12is a microprocessor (designated38inFIG. 6), the function of which will be described while referring toFIG. 6. The microprocessor is powered by a (e.g., 3.6 volt lithium) battery14that is located in the battery housing5alongside the encoder housing3.

A plurality of (e.g., three) electrically-conductive (e.g., brass) connector pins16,18and20(best shown inFIG. 4) extend upwardly from the circuit board12, through the encoder housing3, and into the encoder output terminal housing7to terminate at a corresponding plurality of (e.g., screw head) register output terminals22,24and26. As will also be described when referring toFIG. 6, a plurality of (e.g., three) wires (only one of which28being shown inFIG. 5) are connected to respective ones of the register output terminals22,24and26within the encoder output terminal housing7. By virtue of the foregoing, output signals generated by the microprocessor are provided from the circuit board12via connector pins16,18and20to be carried by the wires connected to respective output terminals22,24and26to indicate when the magnet8rotates with sweep hand54past the sensors A, B and C during one revolution of the sweep hand54around the register plate52.

To this end, the wires (e.g.,28) connected to respective output terminals22,24and26at the encoder output terminal housing7may be connected to a conventional meter interface unit stationed nearby the water meter. By way of example, a suitable meter interface unit to be interfaced with the encoder-type register1of this invention is that known commercially as the Itron Badger. However, the particular meter interface unit is a matter of choice and forms no part of this invention.

The meter interface unit (designated44inFIG. 6) is adapted to communicate with a compatible remote data collector. That is, information regarding the number of revolutions completed by the sweep hand54and the magnet8carried therewith past magnetic sensors A, B and C is stored by the meter interface unit for (e.g., wireless) transmission to the data collector. The remote data collector may be carried by hand, attached to a moving vehicle, or static and mounted at a fixed location, such as a telephone pole, or the like. The information transmitted to the data collector from the meter interface unit can be ultimately made available to utilities, municipalities, or private concerns to indicate water consumption at the monitored water meter for billing, analysis or record-keeping purposes.

Turning now toFIG. 6of the drawings, there is shown a block diagram that is representative of the encoder-type register1ofFIGS. 1-5for automatically collecting information concerning water consumption depending upon the number of revolutions completed by the magnet8with sweep hand54past the sequence of magnetic sensors A, B and C. The magnetic sensors A, B and C are preferably Hall Effect sensors that are spaced equal distances from one another along the bottom of the circuit board (designated12inFIGS. 4 and 5). Each sensor is connected to a first stage transistor amplifier31,32and33. The amplifiers31-33increase the signal amplitude of the magnetic sensors and convert the usual differential DC voltage signal provided by a Hall Effect device that is indicative of a magnetic field to a single (i.e., linear) signal. To minimize power consumption, the Hall Effect magnetic sensors A, B and C and their respective amplifiers31-33are powered only when the microprocessor38requires measurements of the magnetic signals. In this regard, only one magnetic sensor (e.g., A) and the amplifier (e.g.,31) associated therewith are powered at any one time.

The outputs of amplifiers31-33are connected through a common input terminal to a second stage or main amplifier34(e.g., a MCP6001T microchip). The main amplifier34provides additional amplification of the DC voltage signals provided by Hall Effect sensors A, B and C. A temperature sensor36is connected to the main amplifier34to compensate for any temperature drift associated with the amplifiers31-33. The main amplifier34is also powered when magnetic measurements are required by the microprocessor38. A resistive temperature sensor (e.g., a thermistor)36is desirable to monitor the ambient temperature of the encoder-type register1. Amplifiers31-33typically do not contain temperature compensation and therefore, are known to exhibit a DC shift with temperature. The main (second stage) amplifier34amplifies the voltage signals that are sequentially provided thereto by the (first stage) amplifiers31-33and sums each signal with the output of the temperature sensor36.

The temperature compensated output of the main amplifier34is supplied to an analog-to-digital converter (ADC)40. The ADC40is preferably integrated within the microprocessor38. ADC40is responsive to both the DC voltage supplied by the main amplifier34and the DC voltage generated by the temperature sensor36.

Power, control and measurement activities are performed by the microprocessor38. By way of example only, a suitable microprocessor for use herein is part number PIC16F684. The microprocessor38is responsible for controlling the analog circuits, taking measurements of the magnetic sensors A, B and C, determining whether the rotation of the magnet8is in a forward direction past the sequence of sensors A, B and C or in a reverse direction past the sequence of sensors C, B and A, measuring ambient temperature, processing requests for information from the meter interface unit, and managing power consumption to maximize the life of the battery (14inFIGS. 4 and 5). The microprocessor38spends the majority of its time in a low-power sleep mode. Microprocessor38can be awakened to perform its activities on a predetermined regular time basis by means of an onboard clock42or periodically by means of an encoded signal request initiated by the meter interface unit44.

Once it is awakened, the microprocessor38determines whether its wake up was caused by a regular timed signal produced by the onboard clock42or a periodic encoded signal produced by the meter interface unit44. In the event of a timer-induced wake up initiated by clock42, the microprocessor38performs a magnetic sensing task during which measurements are taken of all three magnetic sensors A, B and C. To maximize battery life, measurement of a single magnetic sensor is completed in about 25 to 50 microseconds during which the sensors A, B and C and the first and second stage amplifiers31-34are powered up, the sensor outputs amplified by the first and second stage amplifiers31-34are digitized, and the sensors A, B and C are then powered down. Each sensor value is compared with a predetermined calibration value that is initially stored in the microprocessor38. Where the output of a magnetic sensor is greater than a predetermined deviation from the predetermined calibration value, an indication is provided to the microprocessor38that the magnet8is passing (with the sweep hand) in the vicinity of the measured sensor.

The measured sensor value can be adjusted by a standard software routine to compensate for temperature drift. Because ambient temperature will not change rapidly, the temperature sensor36need only be measured by the microprocessor38on a periodic basis (e.g., once every 15 to 60 minutes).

An internal register46of the microprocessor38records the number of complete rotations made by the magnet8past the sequence of sensors A, B and C. Each time the magnet8moves in a forward direction past sensors A, B and C during a full rotation of the sweep hand, the rotation total that is stored in the register46of microprocessor38is incremented. However, should the magnet8move in a reverse direction past sensors C, B and A (indicative of water backflow through the water meter), then the rotation total stored in register46is decremented.

Rather than counting and reading the accumulated number of rotations of the magnet, the microprocessor38may also generate an output pulse to the meter interface unit44each time the magnet8completes a rotation in a forward direction past the sequence of sensors A, B and C. In the output pulse mode, the microprocessor38includes a backflow accumulator48which suppresses the generation of output pulses following a water backflow event (i.e., when the magnet8travels in a reverse direction past magnetic sensors C, B and A). The backflow accumulator48counts the number of consecutive revolutions of the magnet8in the reverse direction. Output pulses indicative of a subsequent forward flow event will be suppressed until the count of the backflow accumulator48has been decremented to zero.

In the event that the wake up of microprocessor38is not initiated by the onboard clock42, a determination is first made as to the type of wake up request. Encoder-type register1ofFIG. 6supports three different modes of wake up requests. One request is an encoded signal mode initiated by the meter interface device44. A second request is an inductive tone reading mode. The third request is the aforementioned pulse output mode to device44.

In the output pulse mode described above, two of the three wires28connected to the output terminals26(ofFIG. 5) of the encoder-type register1are used to transmit an electronic pulse output from the microprocessor38to the meter interface unit44following each forward flow event. The third wire provides a grounded tamper detect to unit44. In the inductive tone reading mode, an attached inductive touch pad is interrogated by a hand-held reader to obtain a reading of the count stored in register46of microprocessor38. The reader applies a high frequency signal to the touch pad, and the microprocessor38responds by providing a high frequency return signal. An industry standard Sensus Compatible communication technique is employed. In the encoded signal mode, one of the output wires28is a common wire, one is a clock input, and the third is a data output. Once again, a standard Sensus Compatible mode of communication is employed between the register1and meter interface device44.

The microprocessor38keeps track of the number of complete rotations of the magnet8in the forward direction past magnetic sensors A, B and C. The count stored in internal register46is reflective of the volume of water flowing between the inlet and outlet ports58and60of the water meter50ofFIGS. 1 and 2to be consumed by a user. The microprocessor38provides an output signal to the meter interface unit44(during the encoded signal mode) or to the inductive touch pad (during the inductive tone reading mode) which is indicative of the total number of revolutions completed by the magnet8. In the alternative, the microprocessor38may also provide output pulses to the meter interface device44during the pulse output mode following each complete rotation of the magnet8in the forward direction. In this case, the meter interface unit44stores the total number of pulses as an indication of water consumption. The information stored by the meter interface unit44can then be transmitted to a remote data collector as earlier described.

FIG. 7of the drawings shows a preferred schematic circuit for implementing the encoder-type register1ofFIGS. 1-6. Although the encoder-type register1has been shown and described herein as having particular application for use in a water meter to automatically record and transmit information regarding water consumption, the register1of this invention is suitable for use as an add-on accumulator to be interfaced with other visual read-only registers. For example, rather than being carried by a sweep hand, the magnet8can be attached to and rotatable with a rotating disc-like register plate that is common to meters which measure the consumption of electricity.