GB2214306A - Commodity meter - Google Patents

Abstract

A gas meter of the kind having one or more chambers in which a flexible diaphragm is moved back-and-forth has an oscillating flag rod (12) driving a gear box (13). A magnet-carrying disc (16) is rotated by gearbox (13) to open and close an adjacent reed switch (15). Electrical pulses produced by the closing of the switch are applied to correction box (19). Corrections for meter calibration, gas pressure and gas temperature are made in box (19) and a corrected stream of pulses on line (22) applied to drive a mechanical counter (24). An absolute encoding device associated with counter (24) provides for remote reading of the index. On electrical failure, the mechanical index maintains its current value, so that all of the count is not lost. <IMAGE>

Description

COMMODITY METEOR.

This invention relates to commodity meters and more specifically to meters wherein the quantity of commodity passing through is represented by electrical pulses. Commonly, such pulses are applied to be counted by electronic counting means, either adjacent nt the meter or remote from it, to derive a measure of total volume of commodity. In such meters, problems arise if there is a failure of electrical power, because not only does the counting process cease, but the existing count of total measured volume is frequently lost.

This invention provides a commodity meter of the kind in which the volume of the commodity passing through is represented by a stream of electrical pulses, wherein said pulses are applied to drive a mechanical index displaying the total volume, whereby on electrical failure the mechanical index continues to display that volume. Clearly, the electrical pulses will in these circumstances cease, but that volume measured to date will be maintained.

The meter may be a gas meter and include an electronic correction means whereby the stream of pulses is corrected for temperature and/or pressure variations of the gas before application to drive the mechanical index, whereby said index displays a corrected total volume.

A specific embodiment of the invention is shown in the accompanying drawing, which is a diagramnatic representation of part of a gas meter.

The gas meter is of the kind having one or more chambers (not shown) in which a flexible diaphragm is moved back-and-forth by the alternate entry and exit of flowing gas through valves, one of which is shown at (11).

The diaphragm is secured to cause a flag rod (12) to oscillate, this movement being translated through a lever system (14) into a rotational movement applied to a gear box (13). A rotational disc (16) driven from gear box (13) carries magnet means (not shown) which influences a reed switch (15) located adjacent the disc, so that the switch closes once or twice in each revolution of the disc. Each time the switch closes, an electrical pulse appears on electric cable (17) and arrives at correction box (19), each pulse nominally representing a known volume of gas flowing through the meter. Alternatively, the pulses may be derived from the movements of the lever system, without the necessity for a gear box.

Electrical input lines (20) bring electrically coded information concerning the temperature and pressure of the gas flowing in the meter to the correction box (19). This information is used to correct the nominal volume of gas flow represented by the electrical pulses so that a corrected volume measurement is achieved. An output line (22) carries an electrical command signal which may also be in the form of electrical pulses to a small stepping motor (23), causing the motor to rotate at a speed related to the corrected volume of gas flow.

A mechanical counting index (24) of conventional form comprises a series of numeral-bearing drums co-operating to display a decimal number representing the total volume of gas which has passed through the meter.

Motor (23) is connected to drive the counting index at a rate corresponding to the corrected flow so that the index displays a corrected volume.

An output on line (25) allows an electrical signal representing the said corrected volume to be transmitted to a remote reading station.

This electrical signal may be derived from the index by absolute encoding means such as are, for instance, described in our co-pending patent applications Nos. 2 187 010 and 2 187 011.

A replaceable dry electric battery (26) powers the electrical system as required.

All of the items shown on the drawing are located in or on the gas meter, the index (24) being secured to the outer surface of the meter, and the battery (26) being accessible for changing at regular intervals.

In an alternative arrangement, the correction box (19) also contains logic means correcting the stream of pulses for calibration variations.

The motor (23) may be replaced by a solenoid driving a ratchet device causing the index to rotate when the solenoid is energized.

Claims (10)

CLAIMS:

1. A commodity meter of the kind in which the volume of the commodity passing through is represented by a stream of electrical pulses, wherein said pulses are used to drive a mechanical index so that it counts a running value of the commodity volume, whereby on electrical failure the mechanical index maintains its current counted value.

2. A commodity meter as claimed in claim 1, wherein said mechanical index is associated with encoding means, whereby the counted value may be transmitted to a remote reading station.

3. A commodity meter as claimed in claim 1 or claim 2, including electronic correction means connected to apply correction factors to the stream of electrical pulses whereby the mechanical index counts a corrected value.

4. A commodity meter as claimed in claim 3, wherein said correction factors include corrections for meter calibration variations.

5. A commodity meter as claimed in claim 3 or claim 4, wherein said meter is a gas meter, and said correction factors include corrections for variations in temperature and/or pressure of the gas.

6. A commodity meter as claimed in any of claims 1 to 5, wherein said mechanical index is driven by a stepping motor powered by said electrical pulses.

7. A commodity meter as claimed in any of claims 1 to 5, wherein said mechanical index is operated by a solenoid driving a ratchet device.

8. A commodity meter as claimed in any of claims 1 to 7, having a replaceable dry battery for powering the electrical circuits.

9. A commodity meter as claimed in any of claims 1 to 8, wherein said mechanical index counts in decimals and displays a decimal number.

10. A gas meter substantially as described hereinbefore with reference to the accompanying drawing.