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WO1993009417A1 - Systeme de mesure du travail, de la puissance, de la force et du couple - Google Patents

Systeme de mesure du travail, de la puissance, de la force et du couple Download PDF

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Publication number
WO1993009417A1
WO1993009417A1 PCT/GB1992/002002 GB9202002W WO9309417A1 WO 1993009417 A1 WO1993009417 A1 WO 1993009417A1 GB 9202002 W GB9202002 W GB 9202002W WO 9309417 A1 WO9309417 A1 WO 9309417A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
torque
force
work
preset
Prior art date
Application number
PCT/GB1992/002002
Other languages
English (en)
Inventor
Dan Merritt
Original Assignee
Catalytic Igniter Systems Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB919123483A external-priority patent/GB9123483D0/en
Priority claimed from GB919126165A external-priority patent/GB9126165D0/en
Priority claimed from GB929210466A external-priority patent/GB9210466D0/en
Application filed by Catalytic Igniter Systems Limited filed Critical Catalytic Igniter Systems Limited
Publication of WO1993009417A1 publication Critical patent/WO1993009417A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/24—Devices for determining the value of power, e.g. by measuring and simultaneously multiplying the values of torque and revolutions per unit of time, by multiplying the values of tractive or propulsive force and velocity
    • G01L3/242—Devices for determining the value of power, e.g. by measuring and simultaneously multiplying the values of torque and revolutions per unit of time, by multiplying the values of tractive or propulsive force and velocity by measuring and simultaneously multiplying torque and velocity

Definitions

  • the present invention relates to the measurement of accumulated mechanical work energy.
  • the system is particularly suitable in situations where power varies with time during the measurement period.
  • Work energy is associated with either a force moving a distance in the direction of the force or a torque moving through an angle in the direction of the torque.
  • the scientifically correct way to measure mean torque and mean power over a time period is to measure accumulated work first and derive mean power from the ratio work/time and mean torque from the ratio work/angle of rotation.
  • a measurement procedure can allow the cancellation of other forces affecting the motion and hence the indirect measurement of the mass of the vehicle. This can have numerous applications, one example being the automatic weighing of train wagons when on the move.
  • the average journey resistance force can be calculated as well as the average thermal efficiency of the engine measured over the journey. Such measurement when logged over many journeys can be used to monitor the condition of the vehicle and the engine.
  • the present invention can have practical applications, hitherto unexploited, in all the abovementioned fields and more.
  • the way to measure work in a linear system under steady state conditions is to measure force and distance moved in the direction of the force during the measurement period.
  • the method is to measure torque and count the number of revolutions over the measurement period.
  • the practised way of mechanical power measurement is either to measure force and velocity or torque and angular velocity.
  • the power transmitted through a shaft under steady state conditions is calculated by measuring the rotational speed and the torque and then multiplying the two values as shown in equation (5).
  • This can provide an indirect measurement of work energy quantities which can be calculated according to equation (3).
  • the number of shaft revolutions may be counted over the measurement period and multiplied by the steady torque according to equation (4) .
  • the measurement of power is carried out by multiplying the measurement of torque by the measurement of speed at any instant, to give the value of the instantaneous power.
  • This method is used mostly with analogue torque and speed measurements which, when multiplied, yield an analogue value of power.
  • This value can be used to calculate accumulated work by sampling the power value and integrating it at equal time intervals, dictated by an electronic clock, according to equation (7).
  • This method of work measurement can run into operational difficulties when operating at low speeds and particularly when a system undergoes a stop-start sequence of operations. It is also a cumbersome measurement operation requiring two measurements, torque and speed, a multiplication process and an integration process.
  • the force applied by a locomotive in pulling a train can be measured by a force transducer during a period for which the distance travelled is measured. If the traction force and/or speed varies during the measurement period and it is desired to evaluate the total work and/or average power during the measurement period, the force and velocity are measured at a given instant and the power transmitted can be evaluated but only for that instant. A series of such measurements may yield a time-average value for power but for good accuracy a high sampling rate may be required, involving two measurements and a multiplication process for each sample.
  • references herein to distance or distance travelled refer to the angle travelled by a rotating shaft through which the torque is applied, and references to velocity or speed refer to the angular velocity of the rotating shaft.
  • the present invention provides a system for measuring accumulated energy in the form of mechanical work done by a moving force or torque over a preset measurement
  • the present invention also provides a method of measuring accumulated energy in the form of mechanical work done by a moving force or torque over a preset measurement period, the method comprising by:
  • the present invention further provides a system for measuring accumulated energy in the form of mechanical work done by a moving force or torque over a preset measurement period, the system characterised by:
  • the present invention still further provides a method of measuring accumulated energy in the form of mechanical work done by a moving force or torque over a preset measurement period, the method comprising:
  • the first means may be a transducer and the electrical output signal from the transducer may be continuous in time, i.e. an analogue signal. Alternatively it may be in the form of a stream of electrical signals separated in time, i.e. in the form of a digital signal.
  • the digital output from the transducer may be frequency modulated or amplitude modulated.
  • the first means can be a transducer suited to measure the mechanical strain in a shaft or tie rod undergoing stress under the influence of torque or force.
  • the second means is advantageously a gate which opens for a short time, on command from the third means, to allow a measurement signal from the first means to pass from the input terminal of the gate to its output terminal or terminals.
  • the second means may be a device capable of very quickly copying an electrical value at an output from an electrical transducer, for use in a second electrical circuit, following a trigger command from a third electrical circuit.
  • the preferred third means uses a trigger transducer. This may be activated by a rotating device to produce a triggering signal at selected angular intervals during rotation. The angle turned during said intervals is made proportional to the distance travelled by the measured force or to the angle turned by the torque transmitting shaft during said same time interval, the distance being either angular or linear.
  • the rotating device can be a wheel engaged with the surface on which a force is moving or it can be a disc coupled with the shaft which transmits the torque. Alternatively it can be generated electronically in synchronism with the rotating shaft.
  • all the signals passing through the second means are summed to provide said further signal.
  • the invention achieves a measurement of work energy quantity, under non steady state conditions using a simple and accurate practical method based on Equations (6) and (8) effectively using a measurement of a single quantity, force or torque.
  • This simple measurement technique can yield a very accurate measurement of total work, depending on the accuracy of the torque meter the frequency of sampling digital readings and the duration of the measurement period.
  • Equation (12) is similar to equation (11) showing the total amount of work energy is equal to a constant multiplied by the sum of all the force measured values obtained during the period by successive sampling of the force measurement.
  • Figure 1 is a diagrammatic block diagram of a first embodiment of a work measuring system according to the present invention
  • Figure 2 is a diagrammatic illustration of an application of the system of Figure 1 to measure work energy quantity produced by a moving force
  • Figure 3 is a diagrammatic illustration of a second application of the system of Figure 1 to measure work energy quantity produced by a rotating torque using a rotating torque meter;
  • Figure 4 is a diagrammatic illustration of a third application of the system of Figure 1 to measure work energy quantity produced by a rotating torque using a torque measurement through a stationary reacting force;
  • Figure 5 is a block diagram of a modified work measuring
  • Figure 6 is a block diagram similar to Figure 1, of a further embodiment of a work measuring system according to the present invention.
  • Figure 1 shows a preferred form of system for measuring work energy done by a moving force over a selected time period.
  • the system has a force or torque transducer 1 which may be, for example, a strain gauge based load cell for force measurement or a strain gauge torque measuring tube for torque measurement.
  • the electrical output from transducer 1 may be an analogue signal e.g. a voltage proportional to either force or torque, or a digital signal. Where it is an analogue signal it is fed into an A/D (analogue to digital) converter 2 where the measurements are converted to a digital signal.
  • A/D converter 2 analogue to digital converter 2 where the measurements are converted to a digital signal.
  • the output from the A/D converter is sampled through a gate 4 which is actuated by a trigger 3 which operates in a cyclic manner.
  • the trigger 3 may be constructed, for example, as a rotating disc equipped with devices, equi-spa ⁇ ed around its rim, capable of energising a stationary pick-up transducer in proximity to generate trigger pulses.
  • the angle through which the disc rotates between successive trigger events (trigger pulses) is directly proportional to the linear distance covered by the moving force between the said successive triggering events.
  • the disc may conveniently be formed or driven by a wheel rolling along the surface on which the force is engaging for propulsion.
  • the angle through which the disc rotates between successive triggering events is directly proportional to the angle of rotation of the torque- transmitting shaft between the successive triggering events.
  • the rotating disc may conveniently be mechanically
  • the number of trigger events during one revolution of the trigger 3 is chosen according to the extent of the fluctuation in the values of the force or torque being measured and the accuracy required for the work energy measurement.
  • the signals from the trigger 3 control the opening and closing of the gate 4 which allows, when open, the digitised signal representing measurement of either force or torque to be transmitted to a summing circuit 5 where it is added to the grand total value of all the preceding measurements. There is no need for preceding readings to be stored separately, only their sum total at any instant.
  • the time period over which the total work energy is to be measured (measurement period) is controlled by gate 7 which can either be opened and closed manually or controlled by an external automatic controller.
  • the gate 7 opens at the same time as the measurement period starts and closes when the measurement period finishes. When closed, the gate 7 prevents triggering signals reaching the gate 4 and stops further accumulation of readings in the summing circuit 5.
  • a timer 90 measures the time for which gate 7 is open (measurement period) and supplies a signal representing this measurement to calculator 6 to enable the average power over the measurement period to be calculated.
  • the grand total accumulated in 5 is multiplied by a constant in a calculator 6 to indicate the total amount of work done.
  • the calculator also has a digital display facility for displaying the resulting calculation.
  • the value of the constant depends on the number of trigger events per revolution of the trigger 3 and on the calibration constant from volts to Joules, which is programmed into the calculator through a data input facility
  • SUBSTITUTE SHEET After a reading is taken at the end of a measurement period, it can be stored in a memory if desired. To prepare for a subsequent measurement period, the summing circuit 5 is reset to zero by a reset signal from a reset 8 which is activated either manually or automatically in anticipation of the next measurement period.
  • the reading displayed in 6 can, for example, be in the energy unit Joule. Since the quantity of energy measured over an appreciable time interval can be large, the resolution of the measurement can be extremely fine, for example, one Joule in a MegaJoule. However, it is best to display the result with a resolution reflecting the accuracy of the force or torque meters used.
  • the system of Fig.l may include either a subsystem for measuring the volume or mass of fuel used in an engine using a fuel quantity meter 10 or a subsystem for counting the number of trigger pulses using a counter 11, or both.
  • the gate 7 When using meter 10, the gate 7 operates on both meter 10 and gate 4 simultaneously to enable a simultaneous measurement of both work energy output and fuel quantity input.
  • the fuel quantity measurement in digital form is fed into the calculator 6 from the meter 10 at the end of the measurement period.
  • the work quantity is divided by the fuel quantity and then multiplied by a constant factor representing the calorific value of the fuel used.
  • the constant is entered from block 9, the constant data input facility.
  • the system is capable of measuring the average brake thermal efficiency of an engine over the period of measurement, or its inverse in the form of brake specific fuel consumption. If this is done on an engine test bed it can be used to give either a very accurate measurement of nominally steady state thermal efficiency taking into account cycle to cycle variations, including misfires, or a measurement of the overall grand average of brake thermal efficiency over a period when the engine is deliberately made to operate through a sequence of different conditions, including acceleration, idling and overrun.
  • the engine under measurement is an electric motor meter 10 measures the electrical energy input to the motor enabling an efficiency value for the motor, with or without a transmission system, to be calculated over a prolonged period of non steady state operation.
  • Counter 11 counts the number of pulses from trigger 3 during the period of work measurement and supplies a signal representing the count to the calculator 6 to enable the average force or torque over the measurement period to be calculated.
  • the grand total is proportional to the total number of engine revolutions during the same period and can also be used to calculate the average brake work per engine cycle, hence the brake mean effective pressure (BMEP).
  • BMEP brake mean effective pressure
  • Fig.l represents a preferred arrangement of various measurement, triggering and electronic processing elements acting in combination to bring about the processing of measurements according to this invention and that the actual electronic circuitry used can vary according to the design of the instrument.
  • Fig. 2 shows an illustration of a possible use of the
  • SUBSTITUTE SHEET measuring system of Fig.l to measure the work energy involving a moving force, as in a locomotive L used to move a wagon W.
  • the work measured over a journey may be used to calculate the following:
  • the ratio of work to thermal energy supplied gives the elapsed journey average thermal efficiency of the engine. If this is logged over subsequent journeys the condition of the engine can be monitored.
  • the force measuring means is in the form of a force transducer 1 and the trigger 3 is activated by the rotation of a wagon wheel.
  • the force transducer 1 may be located between the axles of the driving wheels where it is attached to the body of the vehicle and the trigger may be located at the corresponding driving wheels.
  • Fig. 3 shows an illustration of a second possible use of the system of Fig. 1, namely that of measuring the work energy involving a rotating torque produced by an internal combustion engine E on a test bed, the engine supplying energy to a dynamometer or brake B.
  • the force measuring means is in the form of a torque transducer 1 and the trigger 3 is directly driven by the engine shaft.
  • the torque transducer may be located on the shafts connecting the differential to the driving wheels and the trigger may be attached to the same shafts.
  • E in Figure 3 represents an electrically powered motor or system and the electrical energy input is measured at the same time as work done then the efficiency of the motor or system can be measured over a prolonged period and logged.
  • Fig. 4 shows an illustration of a further possible use of the measuring system of Fig. 1, namely that of measuring work energy involving a rotating torque through a shaft S which supplies energy to a dynamometer D mounted on trunnion bearings. This allows the reaction torque on the dynamometer casing to be measured by a measuring means in the form of force transducer 1 engaged with a lever which is connected to the dynamometer casing.
  • the trigger 3 is attached to the shaft S transmitting the torque.
  • Fig. 5 is a block diagram showing a measurement system similar to that of Fig. 1 with like parts having like numbers.
  • the quantity accumulated in the summing circuit 5 is measured over a time interval determined by gate 7. This quantity represents the amount of work energy accumulated over a prolonged measurement period.
  • the measurement of an average torque value over a pre-selected number of shaft revolutions is obtained as follows.
  • the output from gate 4 is also sampled through gate 18.
  • Counter 11 monitors trigger 3 and closes gate 18 after a pre ⁇ determined number of trigger signals have been counted by counter 11.
  • gate 18 allows a digitised measurement of torque to be transmitted to the fourth means, a summing circuit 12 where it is added to the grand total value of all the preceding measurements.
  • Gate 18 is controlled to open for a pre-determined number of openings of gate 4, i.e. a pre ⁇ determined number of operations of trigger 3 which are monitored by counter 11.
  • the accumulated work energy, measured in summing circuit 12 is therefore measured over a pre-determined number of shaft revolutions in this way.
  • a value of the average torque over the number of revolutions chosen can be calculated in calculator 6 since the average torque value is only multiplied by a constant which relates to the number of revolutions chosen for the measurement.
  • the constant facility data input 9 is programmed to allow the calculator to display the average torque value in display T.
  • the pre ⁇ determined number of openings of gate 18, monitored by counter 11 yield a measurement of the work energy over that pre ⁇ determined distance. This yields a value of average force over the distance chosen, multiplied by a constant which relates to the distance interval chosen for the measurement.
  • the measurement of an average power value over a pre-selected time period is obtained as follows.
  • the output from gate 4 is also sampled through gate 16 which is actuated by clock 17 to close after a pre-determined time period.
  • gate 16 allows a digitised measurement of either force or torque to be transmitted to a summing circuit 14 where it is added to the grand total value of all the preceding measurements.
  • the accumulated work energy measured in summing circuit 14 is therefore measured over a pre-determined time period, so yielding a value of power averaged over the measurement time period.
  • equation (3) a value of the average power over the time period chosen can be calculated in calculator 6 since the average power value is only multiplied by a constant which relates to the period of time chosen for the measurement.
  • the constant facility data input 9 is programmed to allow the calculator to display the average power value in display P.
  • gate 18(16) The opening and closing of gate 18(16) is effected continuously in a repetitive way.
  • the gate is opened by a signal from a clock 17 (which is applied through a reset 13 in the case of gate 18) .
  • the signal from clock 17 causes reset 13 to zero the value in summing circuit 12(14) just before or at the time of opening gate 18(16).
  • the gate 16 is closed by clock 17 after the predetermined time interval has elapsed from the moment gate 16 is opened.
  • Gate 18 is closed by counter 11 after the pre-determined number of counts has elapsed from the moment gate 18 opened.
  • Gate 18(16) remains closed until a further opening signal is received from clock
  • Clock 17 may be used to control the frequency of measurements and the duration of display of the average value of torque or power measured at each time interval. For example, clock 17 can activate reset 13 to zero the summing circuit 12(14) and to trigger gate 18(16) to open, to start a measurement. Gate
  • the quantity accumulated in summing circuit 12(14) is delivered to the calculator 6, where it is multiplied by the appropriate constant programmed in by the constant data input facility 9.
  • the quantity can be displayed in T or P in appropriate torque, force or power units of measurement, as the case may be.
  • clock 17 can determine the opening and closing of gate 18. The number of counts in counter 11 is then delivered to the calculator 6.
  • the next opening of gate 18(16) by clock 17 which controls reset 13 may be delayed until after a measurement is completed, i.e. after the chosen number of pulses from counter 11 (time interval chosen for clock 17), over which a measurement is taken, plus a further period of time for the display of the measurement on display T(P), to allow time to observe or record the value.
  • the torque or power value may be recorded automatically and stored in an electronic memory.
  • SUBSTITUTE SHEET This procedure is repeated continuously allowing the measurement of average torque, over a pre-selected number of shaft revolutions, or the measurement of force over pre ⁇ selected distance intervals, or the measurement of average power over a preselected time interval, as the case may be.
  • the results displayed on display T or P, in discreet digital steps, may change at the time intervals selected by the pre ⁇ set clock 17, to follow changes in the torque or power delivered by the shaft.
  • the system described can be used to measure average, force values over short distance intervals in the same way and also to yield a grand average force for a complete journey over a longer distance.
  • the system described can also be used to measure average power values over short time intervals in a system where work is produced by a movement of a force the same way, and also to yield a grand average power for a complete journey over a longer distance.
  • a force or torque transducer 1 provides a signal representative of the force or torque being measured whilst a speed transducer 80 produces a velocity signal representative of the velocity of the force or torque.
  • These two signals are multiplied by a multiplier 82 and, where the resulting product signal is not a digital signal, the signal is passed through an A/D converter 2.
  • the resulting product signal is sampled by gate 4 which is opened and closed by clock pulses from a clock 84.
  • the clock 84 generates pulses at a preselected frequency.
  • the sampled signals are summed in summing circuit 5 and the resulting signal is processed in calculator 6 which displays a reading of the amount of work done over the measurement period.
  • the embodiment of Figure 6 can also be used to produce readings of average force or torque and average power over the whole of the measurement period or over selected time periods within the measurement period, as is described with reference to Figure 5.
  • the trigger signals When sampling is on the measurement signal from 1 above - the trigger signals being generated by a device operating in a cyclic manner with an angular speed of rotation proportional or equal to the speed of rotation of the torque transmitting shaft and/ or the linear velocity of a vehicle being driven by the torque transmitting shaft so that the interval between successive trigger events represents either a linear or an angular distance covered by the force or torque during the time interval between the successive trigger events.
  • the present invention also extends the use of the system described to the measurement of torque or force and/or power, averaged over a period of a measurement on the basis of work quantity. It is particularly suitable for the averaging of values of torque and power which fluctuate with time.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)

Abstract

Procédé et système de mesure du travail effectué par une force mobile ou couple soit sur une période de temps de mesure prédéterminée soit sur une distance prédéterminée parcourue, utilisant un transducteur (1) qui mesure la force ou le couple et produit un signal proportionnel à la valeur mesurée. Ce signal peut être numérique ou peut être analogique et converti en un signal numérique dans un convertisseur analogique/numérique (2). Le signal résultant est échantillonné à des intervalles de déclenchement présélectionnés pendant la période de mesure, l'échantillonnage étant commandé par un déclencheur (3) qui est commandé par le mouvement de la force ou du couple de telle sorte que l'intervalle entre les signaux de déclenchement successifs représente une distance parcourue par la force ou le couple. Les valeurs échantillonnées de la force ou du couple sont additionnées dans un circuit d'addition (5) pour produire un signal correspondant à une valeur qui est proportionnelle au travail accumulé effectué par la force ou le couple depuis le début de la période de mesure. Ensuite le signal est traité dans un calculateur (6) et affiché sur un écran (W) sous forme de données de lecture, exprimées par exemple, en unité d'énergie Joule. Le calculateur (6) peut également produire des affichages de la force ou du couple et de l'énergie accumulés sur la période de mesure. Par ailleurs, le travail, la force ou le couple et l'énergie moyens peuvent également être calculés et affichés à des intervalles sélectionnés pendant la période de mesure.
PCT/GB1992/002002 1991-11-02 1992-11-02 Systeme de mesure du travail, de la puissance, de la force et du couple WO1993009417A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB9123483.1 1991-11-02
GB919123483A GB9123483D0 (en) 1991-11-02 1991-11-02 Work energy and power measuring device
GB9126165.1 1991-12-10
GB919126165A GB9126165D0 (en) 1991-12-10 1991-12-10 Work power force and torque measuring system
GB929210466A GB9210466D0 (en) 1992-05-15 1992-05-15 Work energy measuring device
GB9210466.0 1992-05-15

Publications (1)

Publication Number Publication Date
WO1993009417A1 true WO1993009417A1 (fr) 1993-05-13

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Application Number Title Priority Date Filing Date
PCT/GB1992/002002 WO1993009417A1 (fr) 1991-11-02 1992-11-02 Systeme de mesure du travail, de la puissance, de la force et du couple

Country Status (2)

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AU (1) AU2804692A (fr)
WO (1) WO1993009417A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102494820A (zh) * 2011-12-28 2012-06-13 北京市三一重机有限公司 一种电力测功机

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4157658A (en) * 1978-01-17 1979-06-12 Fiber Controls Corporation Engine horsepower measurement system
US5027303A (en) * 1989-07-17 1991-06-25 Witte Don C Measuring apparatus for pedal-crank assembly

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4157658A (en) * 1978-01-17 1979-06-12 Fiber Controls Corporation Engine horsepower measurement system
US5027303A (en) * 1989-07-17 1991-06-25 Witte Don C Measuring apparatus for pedal-crank assembly

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 8, no. 23 (P-251)(1460) 31 January 1984 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102494820A (zh) * 2011-12-28 2012-06-13 北京市三一重机有限公司 一种电力测功机

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