METHOD AND APPARATUS FOR DETERMINING THE MASS OF A FLUID FLOWING THROUGH A FLOW RATE METER IN A CONSUMPTION TIME INTERVAL

Abstract

The mass of a fluid flowing through a flow rate meter at a temperature which fluctuates in a given temperature range is determined by driving an exciter magnet system through the fluid with an exact correlation between the fluid volume flowing there through and the movement path covered by the exciter magnet system, producing a measurement voltage pulse after each passage through a movement path corresponding to a unit volume of the fluid by means of a Wiegand wire and a coil surrounding same, at each measurement time charging a first energy storage means by electric energy contained in each measurement voltage pulse, and using same as operating energy for measurement of the instantaneous temperature of the fluid, producing a temperature value as an integral multiple of the smallest temperature measurement unit to be resolved and an integral count value including said temperature value, and adding same to a sum contained in a non-volatile storage means from the precedingly ascertained count values for forming an ongoing sum in the non-volatile storage means and passing same to a processor which can be supplied with external energy and which calculates therefrom the temperature-corrected delivery volume of the fluid.

Claims

1-13. (canceled)

14. A method of determining a mass of a compressible gas flowing through a flow rate meter, the method comprising: flowing compressible gas through the flow rate meter such that a component of an exciter magnet system is moved through a predetermined movement path; in response to the component completing a movement through the predetermined movement path, causing a measurement voltage pulse to be generated with the exciter magnet system, wherein the measurement voltage pulse is generated at a measurement time, and wherein the measurement voltage pulse comprises a first amount of electric energy; charging, at the measurement time, a first energy storage device with a portion of the first amount of electric energy; and using, at the measurement time, energy stored in the first energy storage device to: (i) measure an instantaneous absolute temperature or a parameter derived therefrom of the compressible gas flowing through the flow rate meter; (ii) produce a temperature value derived from the instantaneous absolute temperature or the parameter derived therefrom; (iii) produce an integer count value including the temperature value; and (iv) add the integer count value to a sum of count values contained in a non-volatile memory.

15. The method of claim 14, further comprising: at a selected transmission time that occurs after the measurement time, providing electric energy to a processor thereby enabling the processor to access the sum of count values contained in the non-volatile memory and then generate a message that is transmittable via a transmitter, wherein the message contains the sum of count values.

16. The method of claim 15, further comprising: at the selected transmission time, enabling the processor to transmit the message via the transmitter.

17. The method of claim 16, wherein energy stored in the first energy storage device is further used, at the measurement time, to: (v) measure a pressure prevailing in a unit volume through which the compressible gas has flowed; (vi) produce a pressure value based on the measured pressure; and (vii) modify the integer count value to include an accounting for the pressure value.

18. The method of claim 14, wherein the instantaneous absolute temperature is measured by a temperature sensor whose output is directly proportional to the instantaneous absolute temperature.

19. The method of claim 14, wherein energy stored in the first energy storage device is further used, at the measurement time, to determine a counter state.

20. The method of claim 14, further comprising: determining a direction of rotation of the component of the exciter magnet system with a Hall element, wherein the Hall element is supplied with electric energy by the first energy storage device.

21. The method of claim 14, further comprising: at the measurement time, converting an analog output signal of a temperature sensor to a digital value that corresponds to the instantaneous absolute temperature.

22. The method of claim 14, wherein the exciter magnet system includes at least two exciter magnets which are shielded outwardly by a ferromagnetic return yoke body.

23. The method of claim 14, wherein the measurement voltage pulse is produced with a Wiegand or pulse wire.

24. The method of claim 14, further comprising: at times other than the measurement time and prior to the component of the exciter magnet system completing the movement through the predetermined movement path, using motion of the component to produce additional voltage pulses that comprise a second amount of electric energy; and charging a second energy storage device with a portion of the second amount of electric energy.

25. The method of claim 14, wherein the first energy storage device comprises a capacitor.

26. An apparatus configured to determine the mass of a compressible gas whose instantaneous absolute temperature can fluctuate in a given temperature range, the apparatus comprising: a flow rate meter comprising a unit volume through which the compressible gas is allowed to pass; an exciter magnet system including a component that is moveable in response to the compressible gas pass through the flow rate meter, wherein there exists an exact correlation between an amount of the compressible gas flowing through the unit volume and a length of a predetermined movement path of the component; a Wiegand or pulse wire arranged in proximity of the exciter magnet system that produces a measurement voltage pulse when the component has completed the predetermined movement path, wherein the measurement voltage pulse is produced at a measurement time; and a first energy storage device in electrical communication with the Wiegand or pulse wire that is charged with the measurement voltage pulse, wherein electric energy contained in the first energy storage device is used at the measurement time to provide power to each of the following: (i) a temperature sensor that is configured to measure an instantaneous absolute temperature or a parameter derived therefrom of the compressible gas flowing through the flow rate meter; (ii) a calculation device configured to produce a temperature value derived from the instantaneous absolute temperature or the parameter derived therefrom as well as produce an integer count value including the temperature value; and (iii) non-volatile computer memory configured to have the integer count value added thereto as a current sum of count values already contained in the non-volatile computer memory.

27. The apparatus of claim 26, further comprising: a processor configured to, at a selected transmission time that occurs after the measurement time, access the current sum of count values from the non-volatile computer memory and then generate a message that contains the current sum of count values.

28. The apparatus of claim 27, further comprising: a transmitter configured to transmit the message to a receiver.

29. The apparatus of claim 28, further comprising: a second energy storage device configured to receive electric energy from the exciter magnet system and with the electric energy stored therein power the processor and transmitter.

30. The apparatus of claim 26, wherein energy stored in the first energy storage device is further used, at the measurement time, to: (v) measure a pressure prevailing in a unit volume through which the compressible gas has flowed; (vi) produce a pressure value based on the measured pressure; and (vii) modify the integer count value to include an accounting for the pressure value.

31. The apparatus of claim 26, further comprising: a temperature sensor whose output is directly proportional to the instantaneous absolute temperature.

32. The apparatus of claim 26, wherein energy stored in the first energy storage device is further used, at the measurement time, to determine a counter state.

33. The apparatus of claim 26, further comprising: a Hall element supplied with electric energy by the first energy storage device to determine a direction of rotation of the component.

34. The apparatus of claim 26, further comprising: an analog to digital converter that converts an output signal of a temperature sensor to a digital value that corresponds to the instantaneous absolute temperature.

Description

[0049] The invention is described hereinafter by means of an embodiment by way of example with reference to the drawing; therein the single FIGURE shows a schematic block circuit diagram of the most essential components, serving to carry out the method according to the invention, of a flow rate meter on the basis of an autonomous rotary sensor.

[0050] To be able to obtain the electric energy required for carrying out the necessary measurement and storage procedures from the kinetic energy of a flowing fluid, there is provided an exciter magnet system 1 which is represented in the FIGURE by a permanent magnet and which in the illustrated embodiment is mounted on a rotor of which only the axis of rotation 3 is indicated in the FIGURE. As indicated by the arrow R, the rotor is caused to rotate by the fluid flow to be detected, by means of a suitable mechanical device (not shown in the FIGURE), in such a way that there is an exact correlation between the fluid volume flowing through the flow rate meter or its measuring chamber or chambers, and the rotary angle covered by the rotor. Disposed in the field of the exciter magnet system 1 is a Wiegand arrangement comprising a Wiegand or pulse wire 5 and a coil 7 which is wound thereon and in which a voltage pulse in induced whenever the exciter magnet system 1 passes through certain angle positions. If the exciter magnet system 1 only consists of a single permanent magnet, then two such voltage pulses are obtained in each full revolution of the rotor, but it is possible for example for six or ten such pulses also to be produced in each full revolution by the use of a plurality of pairs of magnetic poles.

[0051] For the example described here it is assumed that one of the voltage pulses produced in the respective full revolution serves as a measurement voltage pulse, that is to say whenever the rotor has passed through an angle segment .sub.M, of 360, corresponding to a unit volume V.sub.E of the fluid that has flowed through the flow rate meter, the measurement and storage procedures described hereinafter are performed. The moment at which such a measurement voltage pulse occurs is referred to in the present context as the measurement time.

[0052] The circuit units shown in the FIGURE can be divided into two mutually partially overlapping groups 8 and 9, of which the first is enclosed by a rectangle shown in broken lines and the second is enclosed by a rectangle shown in dash-dotted lines.

[0053] Of the circuit units and components in the first group 8, the analog/digital converters 14 and 15 respectively associated with the temperature sensor 11 and the pressure sensor 12, the single Hall element 16 possibly provided for detecting the direction of rotation of the rotor, the counting and storage logic means 17, the non-volatile storage means 19 and the energy management circuit 20 operate each time that there occurs a measurement voltage pulse which charges a first energy storage means 22 which is formed in the FIGURE by a capacitor and which provides that the required electric working energy is available to the above-mentioned units sufficiently long that they ascertain the currently prevailing measurement values for the fluid temperature T.sub.M and the fluid pressure p.sub.M and digitize same and can store the integral count values U.sub.pM and U.sub.TM formed from those measurement values in the counting and storage logic means 17 as an ongoing sum in the non-volatile storage means 19, in which there is possibly also stored a counter status r which is ascertained by the counting and storage logic means 17 and which specifies what is the ordinal number of the measurement voltage pulse, that has occurred in a delivery time interval being considered.

[0054] Production of the ongoing sum is now to be elucidated by a numerical example for the situation where the pressure can be viewed as constantly equal to p.sub.0. If it is assumed that, by virtue of a suitable resolution on the part of the analog/digital converter 14, the temperature measurement value U.sub.TM falls in tenths of a degree and is for example 293.5 Kelvin after passing through a full revolution of the rotor, triggering a measurement voltage pulse, that value is thus multiplied by =10, thus giving an integral count value of 2935 which to form the ongoing sum is added to the numerical value (for example 576365) contained in the non-volatile storage means 19 so that the new ongoing sum now contained in the non-volatile storage means 19 is 579300. If then, when the next measurement voltage pulse occurs, the temperature has increased by two tenths of a degree to 293.7 Kelvin, then 2937 is obtained as the last integral count value and 582237 is obtained as the last ongoing sum.

[0055] In contrast to a conventional flow rate meter whose counting mechanism continues to count by 1 at each passage through the measurement angle segment .sub.M of for example 360, in accordance with the invention the ongoing sum in the non-volatile storage means 19 is increased on each occasion by an integral count value which changes in dependence on the fluid temperature prevailing at the measurement time so that that ongoing sum contains all items of information required to calculate the fluid mass delivered to the consumer. A corresponding consideration also applies in respect of changing pressure measurement values if the fluid pressure value U.sub.pM detected at the respective measurement time can vary.

[0056] If it is assumed that the energy delivered by a measurement voltage pulse is just sufficient to perform the measurement and storage tasks described, which occur at each measurement time, it is then provided that the energy of voltage pulses which are produced between the measurement voltage pulses and which do not trigger any measurement and storage procedures of that kind is cumulated in a second energy storage means 23 which for example is also formed by a capacitor and which at selectable moments in time supplies energy to a transmitter 25 which can operate with radio frequency, infrared light, ultrasound or any other transmission energy, in order for example to wirelessly send the last value of the ongoing sum stored in the non-volatile storage means 19 and optionally the counter status r to a remotely arranged receiver at which then, with an external energy supply, implementation of the calculations required for ascertaining the fluid mass delivered to the consumer in a respective measurement time interval can be effected by means of a processor, a p-controller, a computer or the like.

[0057] If however measurement voltage pulses contain more energy than is needed for the respectively occurring measurement and storage tasks, that excess energy can also be cumulated in the further energy storage means 23 and used in the above-depicted fashion.

[0058] All circuit portions belonging to the first group 8 operate totally autonomously and do not require either a battery or any other external energy supply. Preferably they are combined together in an IC which can also be in the form of a hybrid circuit. In particular the first energy storage means 22 can be integrated in that IC. In general the temperature sensor is a separate component.

[0059] In comparison, a supply with electric energy solely from the first energy storage means 22 is not adequate for the components or circuit units belonging to the second group 9, namely a Hall probe arrangement 30 including a plurality of Hall elements, a multiplexer 31 and an amplifier 32. They therefore require an additional energy source, as is also described in greater detail hereinafter.

[0060] The processor 33 shown in the FIGURE can either be a component of the circuit arrangement disposed directly at the flow rate meter; it is then either to be attributed to the group 9, or it is supplied with electric energy from the further energy storage means 23 so that, from the respectively last value of the ongoing sum stored in the non-volatile storage means 19, it calculates the corresponding values of the delivered mass of fluid and passes same to the transmitter 25 which then sends them for example wirelessly to a remotely arranged receiver. If a receiver can receive the data from a plurality of transmitters (network arrangement) then each of the transmitters sends a dispatcher address identifying it, together with the data required for calculating the delivery volume V.sub.consumption.

[0061] In accordance with a further alternative the processor 33 can be identical to the above-mentioned processor which is arranged at a remotely disposed receiver and for which an external energy supply is provided in any case. The required data which are then transmitted also then include the constants K.sub.1 to K.sub.3 with the included calibration data.

[0062] The Hall probe arrangement, like the Wiegand or pulse wire 5 and the coil 7 wound thereon, is disposed in the field region of the exciter magnet system 1 and serves to cause fine resolution of the angle segments predetermined by the pairs of magnetic poles of the exciter magnet system 1, as is known from the above-mentioned state of the art (multi-turn). The multiplexer 31 serves for single-channel processing of the output signals of the individual Hall elements of the Hall probe arrangement 30, which are amplified in the subsequent amplifier 32 and then fed to the processor 33 which ascertains therefrom in per se manner fine angle values which more precisely describe the respective rotor position.

[0063] For the purposes of that fine resolution there is on the one hand facilitated calibration of the flow rate meter according to the invention, which is implemented at the factory before first bringing the system into operation, in which case the external voltage V.sub.DD is readily available.

[0064] In addition fine resolution can be used for tracing leaks, through which only very small amounts of fluid issue on the consumer side of the flow rate meter. For that purpose a maintenance operative supplies the circuit arrangement of the flow rate meter with external energy for a period of time which for example can be of the order of magnitude of some minutes, and, by means of the fine resolution arrangement, observes whether the angular position of the rotor changes slightly, which points to the presence of a leak, or not. The external energy can be made available in the most widely varying ways, for example by using a battery or a solar cell operated with ambient light.

[0065] Instead of the above-mentioned Hall elements or Hall probes, it is also possible to use other magnetosensitive components, GMR-sensors (GMRgiant magneto resistance).

[0066] For reasons of space and costs, implementation of the apparatus according to the invention is generally preferred with a single Wiegand module, comprising a Wiegand or pulse wire with a coil wound thereon. It is however also possible to envisage solutions with two or more Wiegand modules in place of a Wiegand module supplemented by an additional magnetosensitive element.