Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F13/00—Apparatus for measuring by volume and delivering fluids or fluent solid materials, not provided for in the preceding groups
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
  • G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters

Definitions

• the present invention relates to a device for measuring the amount flowing through and/or the speed of flow of a medium which is pumped by means of a pump unit, which device comprises a drive motor to cause working cycles of the pump unit, a pick-off for detecting said working cycles and transmitting a pick-off signal depending on said working cycles, an electronic unit to record, by means of said pick-off signal, a value proportional to the number of working cycles from which value the amount flowing through and/or the speed of flow can be determined by means of a nominal calibration factor fixed for the pump unit.
• the object of the present invention is to improve the last-mentioned type of measuring technique so as to obtain a satisfactory measuring accuracy.
• the electronic unit includes on the one hand a calibrating unit which can be adjusted to convert said pick-off signal into at least one output signal which represents a certain true calibration factor, calculated on the basis of a certain correction factor for correction of the nominal calibration factor, and on the other hand devices for recording the amount and/or speed of flow of the medium flowing through, adapted to be controlled by the output signal from the calibrating unit.
• Figure 1 shows diagrammatically a pump unit with a measuring and control device according to the invention
• Figure 2 shows, likewise diagrammatically, the principle on which the present device is based
• Figure 3 shows an example of an electronic unit included in the device shown in Figure 1.
• Figure 4 shows an amount calculating unit which is included in the electronic unit shown in Figure 3
• Figure 5 shows a calibrating unit which is likewise included in the electronic unit shown in Figure 3
• Figure 6 shows an example of an embodiment of the calibrating unit shown in Figure 5
• Figures 7 -9 show examples of embodiments of various counters included in the calculating unit shown in Figure 4. Best mode of carrying out the invention:
• Figure 1 shows that the device according to the invention is composed of a pump unit 1 which is adapted to pump a pumpable medium through a conduit 2.
• the pumped medium may be a liquid of varying viscosity but viscous substances or bulk goods in the form of particles are also conceivable in principle.
• the pump unit is of the displacement type, for example a gear pump or impeller pump, that is to say a type which causes transport of the medium in the conduit with a certain quantity per pump cycle.
• a pump unit of rotating type is provided, said pump cycles consisting of revolutions of the shaft 3 of the pump unit.
• the pump movement is brought about by means of a drive motor, in the example shown an electric motor 4 of rotating type, which is adapted to turn the pump shaft 3, with its output shaft 5, in the direction indicated by the arrow 6, which involves pumping the intended medium in the conduits 2 in a certain direction, indicated by an arrow 7.
• a pick-off 8 Connected to the pump shaft 3 is a pick-off 8 to detect and indicate the working cycles of the pump unit 1 , in this case the revolutions executed by the pump shaft 3 and hence by the pump unit.
• the pick-off 8 is adapted to deliver a pick-off signal at its output 9, depending on the- rotation of the pump shaft 3.
• the signal appearing at the output 9 of the pick-off 8 consists of a pulse train in which the number of pulses corresponds to the number of revolutions of the pump unit or a certain portion of a revolution.
• the pick-off 8 can actually be adapted to deliver either one or more pulses per revolution, and in the latter case, each pulse represents a certain angular interval in the pump shaft 3.
• the pulse train thus comes to represent a value of pumped amount which is nevertheless approximate, as will be explained in more detail below.
• an electronic unit 10 which is adapted to receive the pick-off signal and a control unit 46 which is adapted to control the electric motor 4 depending on signals from the electronic unit.
• the control unit 46 has an engaging/ disengaging function to engage and disengage the electric motor 4, that is to say to start and stop the pump unit 1 depending on the measured amount of pumped medium according to the pick-off 8.
• the engagement/disengagement function also activates a magnetically operated valve which is mounted in the conduit 2 after the pump unit 1. This is adapted after delay, to close the conduit when the pump unit is stopped.
• a speed control function with control of the number of revolutions of the electric motor depending on the number of revolutions measured per unit of time by means of the pick-off 8.
• Both the engagement/ disengagement function and the speed control function may consist of units known per se so that these will not be described in detail. Examples of embodiment of the engagement/disengagement function and the speed control function are electro-magnetic relays or a thyristor unit.
• Figure 3 shows an example of an embodiment of the electronic unit 10 which is composed mainly of a calibrating unit 11 which is adapted to receive the pick-off signal delivered by the pick- off 8, a portion counter 12, a trip counter 13, a long-term counter 14 and a device for recording the flow speed 15. All the said units are connected to the output 16 from the calibrating unit, and the portion counter 12 is adapted to deliver, at its output 17, an output signal which can be utilized for control purposes, for example being conveyed to the control unit 46 for its engagement/disengagement function.
• the device for recording the flow speed. 15 is adapted to record the flow speed of the pumped medium.
• the flow speed or more precisely the speed of the electric motor is adjusted, for example by means of a wheel for example at the device for recording the flow speed 15 in order to act on the control unit 11 for control of the electric motor 4 by means of an output signal from its output 18 in a manner known per se.
• the portion counter 12, the trip counter 13 and the long-term counter 14 are mounted, as can best be seen from Figure 4 but is also indicated in Figure 3, in a common quantity calculating unit 19.
• the values measured in all these counters are presented by means of numerical indicators 42 which are stepped on depending on the signal delivered by the pick-off 8 after calibration in the calibrating unit 11 which will be described in more detail below.
• a required portion is preset, that is to say the transport of a required amount of the pumped medium.
• a LOAD button 24 in the form of a switch by means of which the portion counter 12 is loaded with the preset portion value which then appears on the numerical indicator 42 of the portion counter 12. This counts down to zero, and successively presents the remainder of the portion during this counting down.
• a RESET button 25 for the trip counter 13 which is restored by means of this to the zero position so as to be able to indicate directly the amount pumped between two different occasions, while the long-term counter 14 thus indicates the total amount pumped.
• the panel 25 of the calibrating unit 11 is shown by an example in Figure 5.
• This is provided with three setting members in the form of setting knobs 26, 27, 28 for setting the decimal points on the three different counters, that is to say one setting knob 26 is adapted to set the decimal point, that is to say the measuring range for the portion counter 12 and the device for recording the flow speed 15, one knob 27 for corresponding setting of the trip counter 13 and one setting knob 28 for the long-term counter 14.
• the knobs 26, 27, 28 are adapted to be set in four different positions each one representing one position for the decimal point in the respective unit. By means of the knob in each one of its positions, a circuit is closed to ignite a light-emitting diode segment in the form of a point in a corresponding numerical indicator 42 in the respective counter.
• three digit indicators 29 Arranged on the panel 25 are three digit indicators 29 which show a scale factor by means of light-emitting diodes. This is adapted to present a set value of the number of dm per pulse which is delivered from the pick-off 8 and corrected according to the invention in a manner which is described in more detail below.
• the scale factor is adjusted in known manner by means of push-buttons
• FIG. 6 shows an example of the composition of the calibrating unit 11 by means of digital components.
• a bistable trigger 31 which may, for example, be a JK trigger of master-slave type, such as a circuit of the type SN5476.
• This is adapted to receive the pick-off signal at its C input, a clock signal generator 32 in the form of an oscillator, adapted to deliver a clock signal in the form of a pulse train with a suitably selected frequency, and an AND-gate 33, the two inputs of which are connected respectively to the Q output of the trigger 31 and the clock-signal generator 32.
• the 1-input of the trigger is connected to a reference potential, for example +5 V, while the 0-input is earthed.
• a down-counter 30 which is adapted to count down the number of incoming pulses from a preset value, which corresponds to the scale factor, that is to say the number of litres per pulse from the pick-off 8.
• the down-counter 30 is connected on the one hand to the output of the AND-gate 33 and on the other hand to a zero- setting input of the trigger 31, designated by CLEAR, for setting the trigger 31 to zero when the counter 30 has counted down to zero.
• Said pulse train is conveyed to the first output 34 without treatment, while before the outputs 35 and 36, the pulse train is divided by means of three frequency dividers 37, 38.
• the pulse train is divided by means of three frequency dividers 37, 38.
• Figure 7 shows an example of the composition of the portion counter 12
• Figure 8 shows an example of the composition of the trip counter 13.
• the long-term counter 14 can be constructed in the same manner as the trip counter so that it is not shown.
• the portion counter 12 comprises an input
• the trip counter 13 is composed of a number of counters 43 which are coupled in cascade and which in this unit, however, are adapted to record the number of incoming pulses by counting upwards from the zero position.
• each counter unit comprises a number of counters 55, 56, the counting position of which is not presented by means of any numerical indicator because the device has a greater internal accuracy than is necessary in practice.
• Figure 9 shows an example of the composition of the device 15 for recording the flow speed.
• This comprises an input 54 which is connected to the first input 34 of the calibrating unit 11 and five upward-counting decade counters 56, 57, which are coupled in cascade and of which four are each connected to their own numerical indicator 58 via registers 45.
• a timer unit 44 which is adapted to deliver a pulse, for example every 60th second, to each register and after a very short delay of for example a few microparts of a second, also to each counter 57 to set these to zero.
• the pulse train which is delivered from the calibrating unit for each incoming pulse from the pick-off 8.
• the pulses in.
• the pulse train are counted by each decade counter 56, 57 in cascade transferring the counter position to the associated register which serves as a locking circuit.
• This is opened at uniform intervals, in this case every 60th second, by the pulses from the timer unit 44, whereupon the information in the register is transferred to the associated numerical indicator 58 while at the same time the counters are set to zero.
• the device according to the invention is calibrated in the following manner.
• the adjustment of the above-mentioned scale factor, that is to say the number of dmr per pulse from the pick-off 8 is brought about with reference to the following calculation.
• a certain portion amount, for example 5.00 dm 3 is adjusted at the proportioning unit 19 by means of the thumb-wheels 22 after which the LOAD button 24 is pressed in and the pump unit started.
• An output signal is then delivered from the calibrating unit 11 at the output 54 in the form of a pulse train which comprises, for each pulse in the pick-off signal, a number of pulses corresponding to the numerical value for the nominal calibrating factor.
• a control measurement is made of the amount actually flowing through the pump unit 1, the medium flowing through being taken out, for example, via a side pipe at the outlet of the pump unit and measured for example by means of a volume meter, the conduit 2 being kept shut by means of a valve connected to said outlet.
• a correction factor K K is calculated
• This true calibrating factor K V is set at the calibrating unit 11 and can be regarded, with satisfactory accuracy, as constant, until the application is altered, for example as a result of the fact that another medium of different viscosity occurs, whereupon the above calculation of the true calibrating factor is repeated as above.
• the calibrating factor is equal to the scale factor since the pick-off 8 is adapted to deliver one pulse per revolution. With several pulses, for example 10 - 20 pulses per revolution, the scale factor is obtained by division of the calibrating factor by the number of pulses per revolution.
• Block 47 refers to the approximate measurement of the amount/flow speed which is obtained direct from the pick-off 8.
• Block 48 represents the control measurement of the actual amount. This control measurement may be supplemented by a further developed embodiment as discussed in more detail below.
• Block 49 represents the calculation of the correction factor, while block 50 represents the accurate measured value obtained. This is thus obtained by correction of the approximate measuring result by means of the calculated correction factor.
• the device according to the invention is ready for use.
• the portion counter 12 is at zero before the start, otherwise it is set to zero via a reset knob not shown.
• the portion required is set by means of the thumb wheel 22, which setting can be seen from the adjusting unit 21, the decimal point, that is to say the negative power of ten, being set by means of the setting knob 26 on the calibrating unit 11.
• the decimal points for the trip counter 13 and the long-term counter 14, that is to say the required maximum volume, are set by means of the knobs 27 and 28.
• the LOAD button 24 is pressed in whereupon the portion counter 12 is charged so that the numerical indicators 42 show the set value in the starting position.
• a signal is given to the electric motor 4 of the pump unit which drives round the pump unit 1 , whereupon the actual medium is pumped through the conduit 2 while the portion counter counts down by means of the output signal from the calibrating unit 11.
• the counter stops and gives a stop signal to the electric motor 4 and said magnetically operated valve, whereupon the pumping is interrupted.
• the pumping can also be interrupted before the zero position is reached by means of a stop member, not shown, in which case the portion counter shows how much remains of the portion which is to be pumped.
• a new start is effected by means of the LOAD button 24 and the portion measuring continues.
• the pump motor can also be driven without simultaneous portion measuring, by means of a change-over switch not shown, in which case the portion counter is disconnected.
• the portion counter shows the pumped amount in cubic decimetres while the trip counter in the example shown shows the amount in cubic metres and thus forms a summation mechanism for the pumped portions and can, if desired, be reset to zero by means of the RESET button 25.
• the long-term counter shows the sum of the partial measurements effected by the trip counter while at the same time the device for recording the flow speed shows the flow speed on a panel not illustrated.
• the scale factor is set automatically from a unit which, in real time, calculates the calibrating factor with a starting point from measured relevant parameters such as pressure, temperature, density and the like, and the connection between the parameters and the calibrating factor determined by introductory measurements.
• the calibrating unit may be otherwise constructed as can the various meters.
• said determination of the correction factor K K and the true calibrating factor K V can be brought about by means of simple circuits for division and multiplication, in which case, instead of the scale factor, the required amount on the one hand and the true amount on the other hand are set at one unit.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Control Of Positive-Displacement Pumps (AREA)
• Measuring Volume Flow (AREA)
• Paper (AREA)

Priority Applications (6)

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Citations (4)

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• 1980
  • 1980-05-22 JP JP55501234A patent/JPS57501042A/ja active Pending
  • 1980-05-22 DE DE803050395T patent/DE3050395A1/de not_active Ceased
  • 1980-05-22 NL NL8020196A patent/NL8020196A/nl not_active Application Discontinuation
  • 1980-05-22 AU AU59891/80A patent/AU540299B2/en not_active Ceased
  • 1980-05-22 WO PCT/SE1980/000149 patent/WO1981003379A1/en not_active Ceased
  • 1980-05-22 GB GB8217792A patent/GB2097936B/en not_active Expired

Patent Citations (4)

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