WO2009090375A1 - Débitmètre et procédé associé - Google Patents

Débitmètre et procédé associé Download PDF

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Publication number
WO2009090375A1
WO2009090375A1 PCT/GB2009/000087 GB2009000087W WO2009090375A1 WO 2009090375 A1 WO2009090375 A1 WO 2009090375A1 GB 2009000087 W GB2009000087 W GB 2009000087W WO 2009090375 A1 WO2009090375 A1 WO 2009090375A1
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WO
WIPO (PCT)
Prior art keywords
sensor
magnet
meter
piston assembly
piston
Prior art date
Application number
PCT/GB2009/000087
Other languages
English (en)
Inventor
Roy Cuthbert
John Price
Richard Cain
Original Assignee
Webtec Products Ltd
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
Application filed by Webtec Products Ltd filed Critical Webtec Products Ltd
Publication of WO2009090375A1 publication Critical patent/WO2009090375A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/20—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow
    • G01F1/22—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow by variable-area meters, e.g. rotameters
    • G01F1/24—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow by variable-area meters, e.g. rotameters with magnetic or electric coupling to the indicating device

Definitions

  • the invention relates to a liquid-flow meter and a method for measuring liquid flow.
  • a variable orifice flow meter for monitoring fluid flow (of either gas or liquid) is described in US Patent No. 7,130,750 of Racine Federated.
  • a long, tapered piston is axially movable over a distance of about 7.5cm (3 inches) within a cavity through which the fluid flows.
  • the piston is urged by the fluid flow against an opposing force exerted by a spring such that the position of the piston within the cavity indicates the fluid flow rate.
  • the piston carries a magnet.
  • a linear array, or row, of magneto-resistive bridges is positioned alongside and outside the cavity to sense the position of the magnet and thereby produce an electrical signal indicative of the fluid flow. In order to sense the position of the piston over a 7.5cm distance, a linear array of seven magneto-resistive bridges is used.
  • US Patent No. 5,589,769 describes a variety of other uses of a linear array or row of magneto-resistive bridges to monitor the position of an element carrying a permanent magnet, such as a piston within a valve.
  • This valve requires a linear array of 12 magneto-resistive bridges.
  • the invention provides a liquid-flow meter and a method for measuring or sensing liquid flow as defined in the appended independent claims, to which reference should now be made. Preferred or advantageous features of the invention are set out in dependent subclaims.
  • the invention may therefore provide a liquid flow meter comprising a piston assembly that is linearly movable within a cavity containing the liquid, and is urged by a flow of the liquid against a predetermined restoring force, usually provided by the action of a spring.
  • the piston assembly comprises or carries a magnet and the meter is provided with an electrical sensor for generating an output signal dependent on an angular position of the magnet relative to the sensor.
  • the sensor is positioned outside the cavity, and not in contact with the fluid, and is at a sufficient distance from the line of movement of the piston assembly that the sensor output signal is usable to derive the linear position of the piston assembly.
  • the linear position of the piston assembly is related to the flow of liquid urging the piston assembly against the action of the spring, and therefore the sensor output signal is related to the liquid flow rate.
  • An object of the invention is to address the need for a more compact, more reliable, lower cost, flow meter with an electric, or electronic, output. This is particularly desirable in the fluid power and lubrication industries where liquid operating pressures can typically be about 300-400bar (30-40MPa). With an increase in on-board computer-based control in mobile and industrial hydraulic systems, there is a significant need for suitably rugged on-board instrumentation to measure liquid flow under arduous conditions. Consequently, the use of fast-moving parts that are vulnerable to failure should be avoided. Liquids being measured are typically mineral oils (which behave in a Newtonian manner) with kinematic viscosity between 15 and 20OcSt at 40C.
  • fluid power applications can vary over a range of temperatures, typically between 20 and 100 degreesC.
  • the fluids typically follow a negative temperature-viscosity curve and viscosity changes can significantly affect repeatability of measurement.
  • the invention may thus advantageously provide a very compact liquid flow meter that is rugged enough to be permanently installed on a high pressure system that may be subject to considerable vibration, which provides excellent repeatability regardless of temperature and viscosity changes, and uses robust and low-cost sensing technology.
  • the piston assembly may comprise a sharp-edged disc movable within a tapered or frusto-conical portion of the passage through which the liquid flows, which may be termed a metering cavity.
  • the disc, or piston may be tapered, and it may move within a sharp-edged orifice. This may, however, increase the surface area of the piston assembly exposed to the liquid flow and disadvantageously increase its viscosity sensitivity.
  • the movement of the piston assembly may be resisted by a spring, and to reduce any effects of vibration and to allow the meter to be mounted in any orientation, the spring may advantageously be preloaded.
  • a spring may advantageously be preloaded.
  • a portion of the piston may be parallel-sided.
  • the piston assembly also comprises, or carries, a magnet that moves with the piston assembly and is detectable by the sensor positioned outside the passage through which the liquid flows.
  • a powerful magnet should be used in order to enhance the accuracy of the position measurement (for example by permitting the sensor to be positioned further from the line of travel of the magnet) and its resistance to external noise.
  • a rare- earth type of magnet such as a sintered rare-earth magnet, for example of iron-boron, may be used.
  • the surface area of the magnet and any magnet holder is likely to increase the surface area of the piston assembly and may therefore disadvantageously increase the sensitivity of the meter to liquid viscosity.
  • Use of a high-flux magnet may advantageously reduce the volume of the magnet required and therefore advantageously reduce the surface area of the piston assembly and the sensitivity of the meter to viscosity.
  • this problem is addressed by separating the sharp- edged metering orifice from the magnetic carrier or magnet by connecting these two parts of the piston assembly by way of a rod or beam, for example, and directing the fluid flow past the sharp-edged metering orifice but away from the magnetic carrier.
  • the separate portions of the piston assembly implementing the metering and sensing functions may be positioned in separate cavities, or chambers, within the meter. The liquid to - A - be measured flows through a metering cavity, within which the sharp-edged disc or piston is housed.
  • a slender rod or equivalent structure of small surface area extends from the sharp-edged disc or piston and passes from the metering cavity into a substantially-enclosed volume of static liquid within a sensor cavity, and the magnet is coupled to the rod within the sensor cavity.
  • the rod is preferably of substantially smaller diameter or cross-sectional area than the disc or piston. In this way, the liquid does not flow past the magnet, and so the surface area of the piston assembly exposed to the liquid flow is reduced.
  • this structure allows both portions of the piston assembly to be independently optimised; for example, a larger magnet may be used in order to improve the sensitivity of the meter without exposing an increased surface area of the piston assembly to the fluid flow.
  • a larger magnet may be used in order to improve the sensitivity of the meter without exposing an increased surface area of the piston assembly to the fluid flow.
  • This may, for example, either allow a larger magnet to be used to increase magnetic flux, or a larger volume of a lower-performance magnet to be used to achieve a predetermined magnetic flux at reduced cost.
  • the spring against which the piston assembly acts under the influence of the fluid flow may also be housed within the sensing cavity in order to reduce viscosity sensitivity.
  • a further advantage of this structure is that the components within the sensing cavity are effectively encapsulated so that in the event of failure, these components cannot enter the downstream liquid path and cause damage to hydraulic components downstream.
  • a further advantage of this structure is that, because a larger, higher-flux magnet may be used without increasing the viscosity-sensitivity of the meter, larger wall thicknesses for the liquid cavities may be used, which can therefore withstand higher pressure. The meter may therefore be used with higher- pressure liquids than prior-art meters.
  • the stroke, or maximum deflection, of the piston assembly is preferably short.
  • the stroke may be about 30mm or less, preferably about 25mm or less, and particularly preferably about 20mm or less.
  • the geometry of the metering chamber and the disc, and the spring rate of the spring can be predetermined in order to achieve the desired stroke corresponding to the desired range of flow rates.
  • One result of employing a shorter stroke is that the force applied to the piston assembly for each millimetre of stroke is increased, and consequently the pressure drop required to operate the meter may disadvantageously be increased.
  • it might be expected that a short stroke would disadvantageously decrease the measurement sensitivity of the flow meter.
  • the meter of the invention may find particular application in measuring the flow of liquids at high pressures, in which an increased pressure drop required to operate the meter may be more than compensated for by the reduction in size and improved reliability. Nevertheless, since it is desirable not to compromise accuracy, the meter requires good or improved resolution of measurement. According to a further aspect of the invention, this may advantageously be achieved through the use of a single electronic sensor for sensing the angular position of the magnet relative to the sensor.
  • a high-flux magnet such as a NeFeB magnet may therefore be used.
  • this magnet may be in a rectangular form, magnetised across its width.
  • the North and South poles of the magnet may therefore be directed perpendicular to the direction of motion of the piston assembly, and one of these poles may face towards the sensor.
  • the magnet is constrained such that its North-South axis remains in the same plane as the piston assembly moves.
  • the sensor then advantageously senses the change in direction of the magnetic flux as the magnet moves with the piston assembly.
  • the sensor is preferably a magneto-resistive sensor and particularly preferably comprises two superimposed magneto-resistive bridges, offset by an angle such as 45° from each other. Taking readings from the two bridges then provides two readings of angle, 45° apart. These readings can be combined to offer good accuracy over the small meter stroke.
  • the meter may be externally shielded, for example by an iron or low-carbon steel housing that extends over the central metering section, to reduce the meter's sensitivity to any external magnetic fields or magnetic flux.
  • a further advantage of using a magneto-resistive sensor makes use of the temperature compensation characteristics of the sensor, which may enable temperature drift effects to be reduced to a minimum without the need for additional costly temperature measurement and compensation hardware.
  • the angular magneto-resistive sensor is therefore particularly suitable for measuring the small stroke of the meter, particularly where the liquid and the environment are likely to be subject to large temperature swings. It should be noted that, as described above, the liquids in fluid power applications can often vary significantly in temperature, which will impact and vary the operating temperature of the sensor.
  • the use of two magneto-resistive bridges at 45° to each other, or at a predetermined angle to each other, may also advantageously increase the range of angular measurement of the sensor and therefore either allow the sensor to be positioned closer to the sensing cavity or allow the stroke of the meter to be slightly increased without disadvantageously affecting the other advantages of the invention described above.
  • the discussion above describes a uni-directional liquid flow meter.
  • the design could be modified to provide a bi-directional liquid flow meter. This change could be achieved by sharing the stroke of the meter between forward and reverse movement, and altering the geometry of the measurement cavity, although this would halve the resolution of the meter when measuring flow in each direction.
  • a further aspect of the invention provides an alternative structure for sensing the movement of a magnet carried by a piston assembly within a fluid flow meter as described above.
  • piston assembly and the fluid flow path may be arranged as described above but the direction of the North and South poles (the magnetic axis) of the magnet carried by the piston assembly is advantageously aligned parallel to, rather than perpendicular to, the direction of motion of the piston assembly.
  • a sensor assembly mounted outside the fluid flow cavity then comprises a rotatably-mounted follower magnet, rotatable about an axis perpendicular to and offset from the path of the piston assembly.
  • the North-South axis of the follower magnet is perpendicular to its rotational axis and the path of the piston assembly lies in its plane of rotation such that the follower magnet rotates to follow the magnetic field of the magnet carried by the piston assembly.
  • the rotational, or angular, position of the follower magnet at any time is therefore indicative of the position of the piston assembly.
  • the follower magnet is located at or near the mid-point of the path of the piston assembly so that it is substantially anti-parallel to the sensor magnet carried by the piston assembly at the mid-point of the path of the piston assembly and rotates away from this position as the piston assembly moves away from its mid-point.
  • the sensor assembly further comprises an electronic sensor for sensing the angular position of the follower magnet.
  • the sensor is preferably a magneto- resistive sensor and particularly preferably comprises two magneto-resistive bridges offset by an angle such as 45° from each other.
  • the plane of the bridges is parallel to the plane of rotation of the follower magnet.
  • the electronic sensor may be positioned on or close to the axis of rotation of the follower magnet, and in close proximity to the follower magnet, in order to optimise the sensitivity of the sensor to the angular position of the follower magnet, but other positions of the sensor relative to the follower magnet may be implemented and the sensor calibrated appropriately to monitor the orientation of the follower magnet.
  • the follower magnet may be mechanically coupled to a visual indicator, such as a needle of a dial mounted on a housing of the meter.
  • a visual indicator such as a needle of a dial mounted on a housing of the meter.
  • suitable electronic circuitry to monitor the electronic sensors may be implemented by the skilled person, but certain additional advantages of these sensors in embodiments of the invention should be noted.
  • a liquid flow meter of this type should preferably be able to operate at a wide range of temperatures, depending on its environment and the fluid temperature.
  • a temperature compensation system may be required, in which the sensor temperature is monitored and an appropriate correction applied to the sensor output.
  • no temperature sensor may be required to correct the sensor output, thus advantageously simplifying the sensing electronics.
  • Figure 1 is a longitudinal section of a flow meter according to a first embodiment of the invention
  • Figure 2 is a transverse section on A-A of the flow meter of Figure 1 ;
  • Figure 3 is a longitudinal section of a flow meter according to a second embodiment of the invention.
  • Figure 4 is a front view of a flow meter according to a third embodiment of the invention.
  • Figure 5 is a side view of the flow meter of Figure 4.
  • Figure 6 is a longitudinal section of the flow meter of Figures 4 and 5;
  • Figure 7 is a transverse section on C-C of the flow meter of Figures 4, 5 and 6;
  • Figure 8 is a longitudinal section of a flow meter according to a fourth embodiment of the invention.
  • Figure 9 is a transverse section on D-D of the flow meter of Figure 8.
  • Figures 1 and 2 are longitudinal and transverse sections of a first flow meter embodying the invention.
  • the meter is housed within a sensor cavity between a fluid inlet 2 and a fluid outlet 4.
  • a piston assembly is axially slideable within the housing, supported by a bush 6.
  • the piston assembly comprises a sharp- edged disc 8 carried at the upstream end of a rod 10, which is slideable within the bush. Behind the bush, the rod engages with a magnet carrier 12, which carries a magnet 14 (the sensor magnet).
  • a flange extends outwardly from the magnet carrier and abuts a spring 16.
  • the magnet carrier, the magnet and the spring are housed within a substantially cylindrical measurement chamber or sensor cavity 18 which terminates at a small opening 20 leading to the outlet of the meter.
  • the sharp-edged disc is moveable, driven by fluid flow, within a frusto-conical metering cavity 22.
  • fluid flow from the inlet of the meter drives the sharp-edged disc along the metering cavity and thus compresses the spring within the sensor cavity.
  • the magnet is therefore moved along the sensor cavity, through a distance dependent on the fluid flow.
  • the rod 10 moves through the bush 6, it displaces a small volume of fluid within the sensor cavity, which passes in or out of the cavity through the small opening 20.
  • two kidney-shaped passages are used.
  • any number of bypass passages may be used, and they can be of any shape, according to ease of manufacture. Functionally, however, the bypass passages should be of sufficient cross-section and appropriately shaped so as not to limit or restrict fluid flow undesirably.
  • a recess 28 is formed within the wall of the housing for mounting an electrical sensor for generating an output signal dependent on the angular position of the magnet 14 relative to the sensor 30.
  • the sensor is a magneto-resistive sensor comprising two magneto-resistive bridges co-located on the same substrate, but positioned at 45° to each other.
  • the magnet is magnetised across its width, such that the North or South pole faces towards the sensor, as the magnet moves within the sensor cavity past the sensor.
  • the North pole is shown facing towards the sensor.
  • the North and South poles of the magnet are aligned with the sensor, and are positioned within the plane of the magneto- resistive bridges.
  • a suitable sensor for this application is the HMC1512 sensor of Honeywell Sensor Products.
  • This type of sensor is usually implemented as a sensor for detecting rotation of a magnetic field, in which case the provision of two magneto-resistive bridges at 45° to each other, one producing a "sine” output and the other a “cosine” output as the magnetic field rotates, can advantageously be used to derive an angle as a function of the arctangent of the bridge outputs.
  • this type of sensor to detect the linear travel of the magnet within the sensor cavity, allowing a single sensor to detect the travel of the magnet along a greater distance than would be possible with other sensors, and thus allowing the construction of a hydraulic flow meter of enhanced reliability and simplicity because only a single sensor is required.
  • the meter structure in the embodiment is magnetically shielded by a soft iron, or mild steel shroud or casing 32.
  • the upstream end of the metering cavity 22 leads to a parallel-sided passage portion 34 of substantially the same diameter as the sharp-edged disc.
  • the sharp-edged disc At rest, with the spring fully extended, the sharp-edged disc is positioned within this parallel-sided passage portion, as illustrated in Figure 1.
  • the disc When fluid flow starts, the disc is forced out of the parallel-sided passage portion before fluid can flow past the disc, within the tapered metering cavity. This initial movement of the sharp-edged disc advantageously preloads the spring, as described above.
  • Figures 1 and 2 illustrates a further aspect of the invention as follows.
  • FIG. 3 illustrates a second embodiment of the invention, in which the linear movement of the magnet is sensed by a single electronic sensor for sensing the angular position of the magnet relative to the sensor. This embodiment does not, however, illustrate the feature of using one or more bypass channels to decrease viscosity sensitivity.
  • fluid flows from an inlet 2 to an outlet 4 through a substantially cylindrical housing 50.
  • a metering portion of the fluid flow passage comprises a sharp-edged orifice 52.
  • a piston assembly is slideably mounted within the housing and comprises a frusto-conical portion 54 arranged to move within the sharp-edged orifice, driven by the fluid flow.
  • the frusto-conical portion of the piston is connected to a magnet carrier 56 which carries a magnet 58.
  • the opposite end of the magnet carrier engages a helical spring 60 and, driven by the fluid flow, urges the spring against a step 62 surrounding the fluid flow passage.
  • a transducer 64 is positioned alongside, but outside, the portion 66 of the fluid flow passage containing the magnet.
  • the South pole of the magnet is oriented to face towards the transducer. (The magnetic field of the magnet is symmetrical about its North-South axis and so either the North or the South pole may face towards the transducer in practice.)
  • the flow sensor in the second embodiment operates in the same way as in the first embodiment, except that the fluid flow passes alongside the magnet and the spring, in contact with the entire piston assembly, as in conventional flow meters of this geometry.
  • Figures 4 to 7 illustrate a third embodiment of the invention comprising a sensor assembly including a rotating follower magnet and an electronic sensor.
  • Figures 4 and 5 are front and side views of the casing of the flow meter, showing a mechanical meter dial 110 on the front face of the casing. On the dial, the fluid flow rate is indicated by a needle 112.
  • Figures 6 and 7 are longitudinal and transverse sections of the meter.
  • Figure 6 illustrates the internal structure, in which the fluid flows from an inlet 2 to an outlet 4.
  • a piston assembly 114 is positioned within a fixed support 116 such that it is slideable within a cavity 166.
  • the piston assembly forms a sharp-edged orifice, through which the fluid flows in order to meter the fluid flow, and movement of the piston is restrained by a spring 160 seated at its downstream end on a fixed flange 162.
  • the piston assembly comprises a magnet carrier 156, within which is mounted a magnet 100.
  • the magnet is positioned such that its North-South axis is aligned with the direction of motion of the piston, unlike the magnets in the first and second embodiments described above.
  • a rotating follower magnet 102 is secured to a spindle 104.
  • the spindle is mounted for rotation in bearings 106, 108.
  • One end of the spindle extends to the front of the meter housing and carries the needle 112 of the meter dial 110.
  • the North-South axis of the follower magnet is perpendicular to the spindle axis and rotates in a plane that substantially intersects the North-South axis of the sensor magnet 100 carried by the piston assembly.
  • the follower magnet rotates to follow the sensor magnet as the piston assembly is moved by fluid flow through the meter.
  • the needle 112 attached to the follower magnet gives a direct read-out of the fluid flow rate.
  • the meter further comprises an electronic sensor 118 mounted close to the follower magnet within a recess 120 within the meter housing.
  • the sensor 118 detects the angular position of the follower magnet about its axis and thus provides an electrical, or electronic, output of the fluid flow rate.
  • the sensor may be of the same type as the sensor 30 in Figures 1 and 2 or the sensor 64 in Figure 3, although it can be seen that the variation in magnetic field produced by the rotating follower magnet at the position of the sensor 118 is very different from the variation in magnetic field experienced by the sensors in Figures 1 , 2 and 3.
  • the sensor 118 may be a magneto-resistive bridge sensor, optionally of the type comprising two co-located bridges at an angle to each other, suitably calibrated to sense the angular position of the follower magnet.
  • the structure of the follower magnet and its spindle permits, it may be preferable to position the sensor on or near (but still perpendicular to) the rotational axis of the follower magnet, in order to maximise the change in direction in magnetic field detected by the sensor as the follower magnet rotates on its spindle.
  • Figures 8 and 9 are longitudinal and transverse sections of a fourth embodiment of the invention.
  • the flow meter comprises the same hydraulic arrangement as the meter illustrated in Figures 4 to 7, but a different sensor assembly is used.
  • the sensor assembly is similar to those illustrated in Figures 1 , 2 and 3.
  • the magnet carrier 156 carries a magnet 114, the North- South axis of the magnet being perpendicular to the direction of motion of the piston assembly.
  • the meter comprises an electronic sensor 164, comparable to the sensors 30 and 64 illustrated in Figures 1 , 2 and 3, mounted within a recess 166 within the meter housing. Other operational details of this embodiment are the same as in the earlier embodiments.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)

Abstract

Dans un débitmètre destiné à mesurer le débit d'un liquide, un ensemble piston peut se déplacer linéairement dans une cavité qui contient le liquide. Un débit du liquide fait dévier l'ensemble piston en le faisant aller contre une force de rappel prédéterminée. L'ensemble piston comprend un aimant. Un capteur électrique en position fixe par rapport à la cavité génère un signal de sortie selon une position angulaire de l'aimant par rapport au capteur. Le capteur est positionné à une distance suffisante de l'ensemble piston afin de pouvoir utiliser le signal de sortie du capteur pour dériver la position linéaire de l'ensemble piston.
PCT/GB2009/000087 2008-01-14 2009-01-13 Débitmètre et procédé associé WO2009090375A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0800583.7 2008-01-14
GB0800583A GB0800583D0 (en) 2008-01-14 2008-01-14 Flow meter and method

Publications (1)

Publication Number Publication Date
WO2009090375A1 true WO2009090375A1 (fr) 2009-07-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102230813A (zh) * 2011-03-17 2011-11-02 兰州理工大学 一种动态流量计
EP3382399A1 (fr) * 2017-03-31 2018-10-03 NTN-SNR Roulements Dispositif de détection d'un passage de graisse et système de graissage associé

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1917974A (en) * 1930-03-25 1933-07-11 Henry B Inglis Flow meter
US2693111A (en) * 1952-04-30 1954-11-02 Reaction Motors Inc Fuel or propellant gauge
GB2090419A (en) * 1980-12-29 1982-07-07 Hayden Nilos Conflow Ltd Zero adjustment of flowmeters
EP0099712A2 (fr) * 1982-07-15 1984-02-01 Jct Controls Limited Débitmètre
EP0171931A1 (fr) * 1984-07-17 1986-02-19 Hayden Nilos Conflow Limited Instruments avec des aimants mobiles
US20040045368A1 (en) * 2002-08-16 2004-03-11 Levitronix Llc Measuring apparatus to determine the flow of a fluid

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1917974A (en) * 1930-03-25 1933-07-11 Henry B Inglis Flow meter
US2693111A (en) * 1952-04-30 1954-11-02 Reaction Motors Inc Fuel or propellant gauge
GB2090419A (en) * 1980-12-29 1982-07-07 Hayden Nilos Conflow Ltd Zero adjustment of flowmeters
EP0099712A2 (fr) * 1982-07-15 1984-02-01 Jct Controls Limited Débitmètre
EP0171931A1 (fr) * 1984-07-17 1986-02-19 Hayden Nilos Conflow Limited Instruments avec des aimants mobiles
US20040045368A1 (en) * 2002-08-16 2004-03-11 Levitronix Llc Measuring apparatus to determine the flow of a fluid

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102230813A (zh) * 2011-03-17 2011-11-02 兰州理工大学 一种动态流量计
EP3382399A1 (fr) * 2017-03-31 2018-10-03 NTN-SNR Roulements Dispositif de détection d'un passage de graisse et système de graissage associé
FR3064740A1 (fr) * 2017-03-31 2018-10-05 Ntn-Snr Roulements Dispositif de detection d’un passage de graisse et systeme de graissage associe

Also Published As

Publication number Publication date
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