CA2068379A1 - Magnetic drive system, and a meter, in particular a water meter, including such a system - Google Patents
Magnetic drive system, and a meter, in particular a water meter, including such a systemInfo
- Publication number
- CA2068379A1 CA2068379A1 CA002068379A CA2068379A CA2068379A1 CA 2068379 A1 CA2068379 A1 CA 2068379A1 CA 002068379 A CA002068379 A CA 002068379A CA 2068379 A CA2068379 A CA 2068379A CA 2068379 A1 CA2068379 A1 CA 2068379A1
- Authority
- CA
- Canada
- Prior art keywords
- magnets
- ring
- drive system
- rings
- magnetic drive
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title abstract description 15
- 238000012216 screening Methods 0.000 claims description 6
- 239000000696 magnetic material Substances 0.000 claims description 5
- 239000012530 fluid Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 230000003071 parasitic effect Effects 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K49/00—Dynamo-electric clutches; Dynamo-electric brakes
- H02K49/10—Dynamo-electric clutches; Dynamo-electric brakes of the permanent-magnet type
- H02K49/104—Magnetic couplings consisting of only two coaxial rotary elements, i.e. the driving element and the driven element
- H02K49/106—Magnetic couplings consisting of only two coaxial rotary elements, i.e. the driving element and the driven element with a radial air gap
-
- 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
- G01F1/56—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 electric or magnetic effects
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/02—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using mechanical means
- G01D5/06—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using mechanical means acting through a wall or enclosure, e.g. by bellows, by magnetic coupling
-
- 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
- G01F1/06—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 using rotating vanes with tangential admission
- G01F1/075—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 using rotating vanes with tangential admission with magnetic or electromagnetic coupling to the indicating device
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/06—Indicating or recording devices
- G01F15/065—Indicating or recording devices with transmission devices, e.g. mechanical
- G01F15/066—Indicating or recording devices with transmission devices, e.g. mechanical involving magnetic transmission devices
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/12—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas
- H02K5/128—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas using air-gap sleeves or air-gap discs
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measuring Volume Flow (AREA)
- Details Of Flowmeters (AREA)
- Dynamo-Electric Clutches, Dynamo-Electric Brakes (AREA)
Abstract
A B S T R A C T
A magnetic drive system comprising two concentric rings (32, 36) of magnets disposed in such a manner that the forces exerted by one ring (32) on the other (36) are repulsive, the number of magnets being the same in both rings and being sufficient to ensure that the inner ring (36) is automatically centered relative to the outer ring (32), rotary motion of one of the rings about its center of axis driving the other ring in rotation, and a meter including such a magnetic drive system.
The invention is particularly applicable to water meters.
A magnetic drive system comprising two concentric rings (32, 36) of magnets disposed in such a manner that the forces exerted by one ring (32) on the other (36) are repulsive, the number of magnets being the same in both rings and being sufficient to ensure that the inner ring (36) is automatically centered relative to the outer ring (32), rotary motion of one of the rings about its center of axis driving the other ring in rotation, and a meter including such a magnetic drive system.
The invention is particularly applicable to water meters.
Description
- 2 ~ 7 ~
A MAGNETIC DP~IVE SYSTEM, AND A METER, IN PARTICULAR A WATER
METER, INCLUDING SUCH A SYSTEM
The present invention relates to a magnetic drive system and to a meter, in particular a water meter, includir~ such a 5 system.
Several magnetic drive systems are known that are used, in particular, for transmitting motion through a wall separating two fluids having different physical or chemical characteristics or different destinations, e.g. in pumps, flow lO rate meters, or fluid meters.
In a first known system using face-to-face drive, a first magnet faces a second magnet. Rotation of tha first magnet causes the second magnet to rotate by attraction or by repulsion, depending on how the poles are disposed.
Face-to-face drive is sensitive to external magne-tic fields that can disturb the operation of the apparatus or the measurement of the meter.
In addition, sensitivity is limited because mechanical or magnetic eccentricity gives rise to lateral forces on the 20 bearings supporting the shafts secured to the magnets.
A second known system makes use of concentric drive and comprises a first series of magnets disposed in a ring and surrounding a second series of magnets likewise disposed in a ring. Each magnet in the first ring faces a magnet in the 25 second ring, with a north pole in one rin~ facing a south pole in the other.
Each of the rings is secured to a shaft supported by bearings.
When one of the rin~s is caused to rotate, the other is 30 driven under drive due to magnetic attraction.
Such a system is relatively insensitive to possible disturbances due to external magnetic fields. In addition, beca~se of the strong drive torgue, it suffers relatively little from slip (which may occur, for example, in a water 35 meter when the fluid accelerates suddenly).
In known concentric systems, the magnets of the different `
rings attract one another perpendicularly to the axis of , , -`` 20~37~
rotation. Unfortunately, lateral attraction in some par-ticular direction always subsists because of mechanical causes such as operating clearance. This lateral attraction is compensated by reaction in -t:he bearings supporting the shafts.
Unfortunately, the resulting interfering torque can be very large, thereby limiting the range over which such a system can be used in spite of the other advantages is provides. For example, the use of such a system in a water meter is limited to meters for usa at high flow rates (positive displacement 10 meters), since the large friction forces of the bearings make small flows impossible to measure.
The present invention mitigates these drawbacks. An object of the present invention is to provide a magnetic drive system of the concentric type which is relatively insensitive 15 to external magnetic disturbances, and which is subjected relatively little to asymmetrical lateral forces and which consequently has increased sensitivity, thereby enabling it to be used in low flow rate water meters, for example.
Another ob;ect of the invention is to provide a magnetic 20 drive system which does not slip even when subjected to sudden accelerations.
Another object of the invention is to provide a magnetic drive system which is simple to implement and cheap.
More precisely, tha present invention provides a magnetic drive system comprising two concentric rings of magnets; same-type poles of the magnets of the inner ring pointing outwards from the inner ring, and the poles of the same type of the magnets of the outer ring pointing inwards from the outer ring, the number of magnets in each of the rings being the same and 30 being suf~icient to ensure that the inner ring is automatically centered relative -to the outer ring, rotary motion of one of the rings about its central axis causing the other ring to be driven in rotation.
The repulsive forces acting between the magnets of each ring position one of the rings relative to the other.
In a preferred embodiment, the magnets in each of the rings are uniformly distributed around the circumference of the - : .
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corresponding ring, the magnets of the outer ring being identical to one another, and the magnets of the inner ring being identical to one another.
In a particular embodiment, the magnets have an angular 5 extent such that the magnets of the two rings overlap partially.
In a preferred embodiment, each ring includes at least four magnets.
I-t appears that if the rings include fewer than four 10 magnets, the attraction between opposite poles of the magnets in different rings may be at least of the same order of magnitude and sometimes even greater than the repulsive forces.
As a result there is a non-negligible possibility of parasitic lateral forces being cxeated that impair the centering of the 15 rings rela-tive -to each other. `~
In an advantageous embodiment, the magnets of the outer ring extend over a height greater than the height of the magnets of the inner ring.
As a result, the screening effect of the outer ring is 20 more effective, thereby making the system even less sensitive to external magnetic fields.
In a variant embodiment, the radial pIanes of the inner and outer rings are offset so as to set up oppositely direc-ted orces that are substantially axial and that are applied to the 25 rings. These forces are used to keep the rings in place while they rotate about the pivots.
In a particular embodiment, a screening shell of magnetic material covers the outer ring.
This screening shell provides total insensitivity to 30 external magnetic disturbances. Since the shell is secured to, and overlies the outer ring, there is no risk of lateral attraction giving rise to a parasitic lateral torque, which risk would xemain if the shell were stationary and thus not secured to the ring.
The present invention also provides a me-ter of the type comprising a first chamber and a second chambex that are separated from each other by a sealed non-magnetic wall, and ~ ~ .
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further including a magnetic ~rive system of the invention, the wall forming a housing containing the inner ring of magnets, with the outer ring o magnets surrounding said housing.
In a particular embodiment of a meter of the invention, 5 each ring of magnets is secured to a shat, the meter further including an axial pivot on either side of the bottom of the housing, which pivots are terminated by respective points on which the shaft rests.
These pivots serve to reduce friction during rotation of lO the rings.
In a variant embodiment of the meter, the inner ring of magnets is connected to a totalizing counter and the outer ring is connected to an axial turbine.
The characteristics and advantages of the invention appear 15 more clearly on reading the following description given by way of explanatory and non-limiting example and made with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic section through a water meter of the invention;
Figure 2 is a diagrammatic plan view of a magnetic drive system of the invention; ~ -Figure 3 is a diagrammatic plan view of a variant :
embodiment of a magnetic drive system of the invention; and Figure 4 is a diagrammatic section through a magnetic 25 drive system of the invention.
The magnetic drive system of the invention is described below in its application to a water meter.
A water meter embodying the invention is described with reference to Figure 1. The meter comprises a first chamber 10 30 and a second chamber 12 which are separated by a non-magnetic watertight wall 14.
Water penetrates into the first chamber 10 via an inlet 16 ~`
; and it leaves via an outlet 18. The fluid flowing through the first chamber 10 rotates an axial turbine 20. The turbine may 35 be made of a material whose density is close to tha-t of water, for example it may have a relative density substantially equal to 0.9. When the meter con-tains water but the water is not ' , -' ' : '- ' ' ~: : - .
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-` ~068a7~
flowing, the turbine 20 rests against the bottom of the chamber lO via an abutment 22.
The first chamber lO is provided with baffles 24 disposed on either side of the turbine 20 both on the bottom and on the 5 top of the chamber 10. When the fluid is flowing, these baffles set up eddies and turbulence that lift the turbine and maintain it in an e~uilibrium position.
The turbine 20 has an axial shaft 26 provided with an axial duct 2~. A non-magnetic support 30 is fixed to the end 10 of the shaft 26.
A ring 32 of magnets centered on the turbine axis is ixed to the support 30. This ring of magnets may be made, for example, of sintered magnetic material, e.g. ferrite or plasto-ferrite, in which a magnetic field is induced at locations that 15 are to be magnetized. This known technique thus makes it possible to obtain magnets having magnetization around the circumference of the ring of magnets that is determined both in polarity and in distribution. The ring may also be made using a non magnetic support provided with housings around its 20 circumference in which magnets are received.
In the embodiment shown in Figure 1, a screening shell 34 of magnetic material, e.g. nickel or soft iron, covers the ring of magnets 32.
The ring of magnets 32 secured to the turbine 20 25 constitutes the driving portion of the magnetic drive system of the meter. The driven portion is constituted by a second ring of magnets 36 inside the first ring 32 but situated in the second chamber 12, and more precisely in an axial housing 38 ~-formed in the separating wall 14.
The second ring of magnets 38 may be constituted by a cylindrical support of non-magnetic material provided with housings around its circumference in which stick-shaped magnets -are rec~ived, for example. ~ -The inner ring 36 and the outer ring 32 are concen-tric and are capable o rotating about the main axis AA which is the axis of rotation of the turbine 20. ~;
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According to the invention, the magnetic drive system is of the repulsive type, and each ring includes at least four - magnets.
Figure 2 is a plan view of a first variant embodiment of such a drive system.
The outer firs-t ring 32 comprises ~our identical magnets referenced 32a, 32b, 32c, and 32d which are uniformly distri~uted around the circumference of the ring.
The inner, second ring 36 likewise comprises four identical magnets referenced 36a, 36b, 36c, and 36d which are uniformly distributed around the circumference of the ring.
The drive system is of the repulsive type: that means that poles of the same type (e.g. north, marked N in Figure 2) of~
the magnets 36a to 36d of the inner ring 36 all point outwards from the ring 36, while the poles of the same type (north) of the magnets 32a to 32d of the outer ring 32 all point inwards from the outer ring 32.
In eguilibrium, the repulsive forces acting between the same type poles of the two rings cause the rings to be~
20 automatically centered relative to each other, with the greatest possible distance between maintained between the magnets of the inner ring 36 and the magnets of the outer rLng ~; ;
32. This automatic centering serves to reduce parasitic lateral forces, thereby improving the sensitivity of the meter, as can be seen in Figure 2 where the angular extent of the magne-ts is such that the two rings overlap partially. Thus, one end of the magnet 32a (for example) faces one end of the magnet 36a (overlap referenced rl) while the other end of the magnet 32a overlaps one end of the magnet 36b (overlap 30 referenced r2).
This overlap serves to improve the stability of the concentric positioning of the two rings.
Figure 3 shows another variant embodiment having six, uniformly-distributed, identical magnets per ring (referenced 32a to 32f and 36a~to~36f). In this example, the magnets point so that the inner ring is automatically centered relative to the outer ring under the effect of repulsion between the .
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magnets in the two rings, however the magnets do not overlap, since there are suf-fi.cient rnagnets to provide sufficient stability for automatic centering.
Figure 4 is a diagrammatic section through a drive system 5 of the invention in which it can be seen that the magnets of the outer ring 32 extend over a greater height than do the magnets of the inner ring 36. This disposit:ion -together with the screening shell 34 ensures that the system is insensitive to external disturbing magnetic fields.
Figure 4 also shows that the radial plane Pi passing halfway up through the inner ring 36 is offset relative to the radial plane Pe passing halfway up through the outer ring 32, and is situatèd beneath it. In this way, a pair of oppositely directed and substantially axial forces Fe and Fi acts on the 15 rings 32 and 36. The force Fe urges the outer ring 32 upwards (when the system is oriented as shown in Figure 4), while the force Fi urges the inner ring 36 downwards.
The inner ring 36 is secured to an axial shaft 40 having an axial duct 42.
The end wall of the duct 42 is supported on the pointed tip of an axial pivot 44 which is fixed to the bottom of the housing 38 in the wall 14. Sincs the contact area between the shaft 40 and the pivot 44 is small, friction is also small and the force Fi applied to the ring 36 provides good overall 25 retention.
It can be seen in Figure l that the structure is identical for the driving ring. An axial pivot 46 terminates in a pointed tip and extends into the first chamber 10 with the bottom of the duct 28 engaging said tip when fluid flows 30 through the first chamber 10. Friction between the tip of the pivot 46 and the shaft is likewise small with the force Fe holding the assembly together.
It will thus be understood that when fluid flows through the chamber 10, the turbine 20 rotates about the pivot 46 (axis 35 AA), thereby driving the outer ring 32 which is secured thereto. Because of the repulsion force between the maynets, the inner ring 36 is caused to rotate about the pivot 44 which is accurately aligned with the pivot 46 (on axis AA).
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The shaft 40 secured to the inner ring 36 is connected to ~;~
a counter 48.
Various conventional instruments can be seen in Figure 1 for calibration purposes and for reading the measurements 5 performed: a stroboscopic calibration wheel 50, a measuring pointer 52, and a digitcal read-out counter S4.
The magnetic drive system which is applied to a water meter in the example described is equally applicable to other types of meter and even to other types of device, e.g. a lO pumping assembly, without going beyond the ambit o~ the invention.
'~ ' :: : :
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.
A MAGNETIC DP~IVE SYSTEM, AND A METER, IN PARTICULAR A WATER
METER, INCLUDING SUCH A SYSTEM
The present invention relates to a magnetic drive system and to a meter, in particular a water meter, includir~ such a 5 system.
Several magnetic drive systems are known that are used, in particular, for transmitting motion through a wall separating two fluids having different physical or chemical characteristics or different destinations, e.g. in pumps, flow lO rate meters, or fluid meters.
In a first known system using face-to-face drive, a first magnet faces a second magnet. Rotation of tha first magnet causes the second magnet to rotate by attraction or by repulsion, depending on how the poles are disposed.
Face-to-face drive is sensitive to external magne-tic fields that can disturb the operation of the apparatus or the measurement of the meter.
In addition, sensitivity is limited because mechanical or magnetic eccentricity gives rise to lateral forces on the 20 bearings supporting the shafts secured to the magnets.
A second known system makes use of concentric drive and comprises a first series of magnets disposed in a ring and surrounding a second series of magnets likewise disposed in a ring. Each magnet in the first ring faces a magnet in the 25 second ring, with a north pole in one rin~ facing a south pole in the other.
Each of the rings is secured to a shaft supported by bearings.
When one of the rin~s is caused to rotate, the other is 30 driven under drive due to magnetic attraction.
Such a system is relatively insensitive to possible disturbances due to external magnetic fields. In addition, beca~se of the strong drive torgue, it suffers relatively little from slip (which may occur, for example, in a water 35 meter when the fluid accelerates suddenly).
In known concentric systems, the magnets of the different `
rings attract one another perpendicularly to the axis of , , -`` 20~37~
rotation. Unfortunately, lateral attraction in some par-ticular direction always subsists because of mechanical causes such as operating clearance. This lateral attraction is compensated by reaction in -t:he bearings supporting the shafts.
Unfortunately, the resulting interfering torque can be very large, thereby limiting the range over which such a system can be used in spite of the other advantages is provides. For example, the use of such a system in a water meter is limited to meters for usa at high flow rates (positive displacement 10 meters), since the large friction forces of the bearings make small flows impossible to measure.
The present invention mitigates these drawbacks. An object of the present invention is to provide a magnetic drive system of the concentric type which is relatively insensitive 15 to external magnetic disturbances, and which is subjected relatively little to asymmetrical lateral forces and which consequently has increased sensitivity, thereby enabling it to be used in low flow rate water meters, for example.
Another ob;ect of the invention is to provide a magnetic 20 drive system which does not slip even when subjected to sudden accelerations.
Another object of the invention is to provide a magnetic drive system which is simple to implement and cheap.
More precisely, tha present invention provides a magnetic drive system comprising two concentric rings of magnets; same-type poles of the magnets of the inner ring pointing outwards from the inner ring, and the poles of the same type of the magnets of the outer ring pointing inwards from the outer ring, the number of magnets in each of the rings being the same and 30 being suf~icient to ensure that the inner ring is automatically centered relative -to the outer ring, rotary motion of one of the rings about its central axis causing the other ring to be driven in rotation.
The repulsive forces acting between the magnets of each ring position one of the rings relative to the other.
In a preferred embodiment, the magnets in each of the rings are uniformly distributed around the circumference of the - : .
, .
., .
. : :
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2 ~ 7 ~
corresponding ring, the magnets of the outer ring being identical to one another, and the magnets of the inner ring being identical to one another.
In a particular embodiment, the magnets have an angular 5 extent such that the magnets of the two rings overlap partially.
In a preferred embodiment, each ring includes at least four magnets.
I-t appears that if the rings include fewer than four 10 magnets, the attraction between opposite poles of the magnets in different rings may be at least of the same order of magnitude and sometimes even greater than the repulsive forces.
As a result there is a non-negligible possibility of parasitic lateral forces being cxeated that impair the centering of the 15 rings rela-tive -to each other. `~
In an advantageous embodiment, the magnets of the outer ring extend over a height greater than the height of the magnets of the inner ring.
As a result, the screening effect of the outer ring is 20 more effective, thereby making the system even less sensitive to external magnetic fields.
In a variant embodiment, the radial pIanes of the inner and outer rings are offset so as to set up oppositely direc-ted orces that are substantially axial and that are applied to the 25 rings. These forces are used to keep the rings in place while they rotate about the pivots.
In a particular embodiment, a screening shell of magnetic material covers the outer ring.
This screening shell provides total insensitivity to 30 external magnetic disturbances. Since the shell is secured to, and overlies the outer ring, there is no risk of lateral attraction giving rise to a parasitic lateral torque, which risk would xemain if the shell were stationary and thus not secured to the ring.
The present invention also provides a me-ter of the type comprising a first chamber and a second chambex that are separated from each other by a sealed non-magnetic wall, and ~ ~ .
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further including a magnetic ~rive system of the invention, the wall forming a housing containing the inner ring of magnets, with the outer ring o magnets surrounding said housing.
In a particular embodiment of a meter of the invention, 5 each ring of magnets is secured to a shat, the meter further including an axial pivot on either side of the bottom of the housing, which pivots are terminated by respective points on which the shaft rests.
These pivots serve to reduce friction during rotation of lO the rings.
In a variant embodiment of the meter, the inner ring of magnets is connected to a totalizing counter and the outer ring is connected to an axial turbine.
The characteristics and advantages of the invention appear 15 more clearly on reading the following description given by way of explanatory and non-limiting example and made with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic section through a water meter of the invention;
Figure 2 is a diagrammatic plan view of a magnetic drive system of the invention; ~ -Figure 3 is a diagrammatic plan view of a variant :
embodiment of a magnetic drive system of the invention; and Figure 4 is a diagrammatic section through a magnetic 25 drive system of the invention.
The magnetic drive system of the invention is described below in its application to a water meter.
A water meter embodying the invention is described with reference to Figure 1. The meter comprises a first chamber 10 30 and a second chamber 12 which are separated by a non-magnetic watertight wall 14.
Water penetrates into the first chamber 10 via an inlet 16 ~`
; and it leaves via an outlet 18. The fluid flowing through the first chamber 10 rotates an axial turbine 20. The turbine may 35 be made of a material whose density is close to tha-t of water, for example it may have a relative density substantially equal to 0.9. When the meter con-tains water but the water is not ' , -' ' : '- ' ' ~: : - .
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flowing, the turbine 20 rests against the bottom of the chamber lO via an abutment 22.
The first chamber lO is provided with baffles 24 disposed on either side of the turbine 20 both on the bottom and on the 5 top of the chamber 10. When the fluid is flowing, these baffles set up eddies and turbulence that lift the turbine and maintain it in an e~uilibrium position.
The turbine 20 has an axial shaft 26 provided with an axial duct 2~. A non-magnetic support 30 is fixed to the end 10 of the shaft 26.
A ring 32 of magnets centered on the turbine axis is ixed to the support 30. This ring of magnets may be made, for example, of sintered magnetic material, e.g. ferrite or plasto-ferrite, in which a magnetic field is induced at locations that 15 are to be magnetized. This known technique thus makes it possible to obtain magnets having magnetization around the circumference of the ring of magnets that is determined both in polarity and in distribution. The ring may also be made using a non magnetic support provided with housings around its 20 circumference in which magnets are received.
In the embodiment shown in Figure 1, a screening shell 34 of magnetic material, e.g. nickel or soft iron, covers the ring of magnets 32.
The ring of magnets 32 secured to the turbine 20 25 constitutes the driving portion of the magnetic drive system of the meter. The driven portion is constituted by a second ring of magnets 36 inside the first ring 32 but situated in the second chamber 12, and more precisely in an axial housing 38 ~-formed in the separating wall 14.
The second ring of magnets 38 may be constituted by a cylindrical support of non-magnetic material provided with housings around its circumference in which stick-shaped magnets -are rec~ived, for example. ~ -The inner ring 36 and the outer ring 32 are concen-tric and are capable o rotating about the main axis AA which is the axis of rotation of the turbine 20. ~;
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According to the invention, the magnetic drive system is of the repulsive type, and each ring includes at least four - magnets.
Figure 2 is a plan view of a first variant embodiment of such a drive system.
The outer firs-t ring 32 comprises ~our identical magnets referenced 32a, 32b, 32c, and 32d which are uniformly distri~uted around the circumference of the ring.
The inner, second ring 36 likewise comprises four identical magnets referenced 36a, 36b, 36c, and 36d which are uniformly distributed around the circumference of the ring.
The drive system is of the repulsive type: that means that poles of the same type (e.g. north, marked N in Figure 2) of~
the magnets 36a to 36d of the inner ring 36 all point outwards from the ring 36, while the poles of the same type (north) of the magnets 32a to 32d of the outer ring 32 all point inwards from the outer ring 32.
In eguilibrium, the repulsive forces acting between the same type poles of the two rings cause the rings to be~
20 automatically centered relative to each other, with the greatest possible distance between maintained between the magnets of the inner ring 36 and the magnets of the outer rLng ~; ;
32. This automatic centering serves to reduce parasitic lateral forces, thereby improving the sensitivity of the meter, as can be seen in Figure 2 where the angular extent of the magne-ts is such that the two rings overlap partially. Thus, one end of the magnet 32a (for example) faces one end of the magnet 36a (overlap referenced rl) while the other end of the magnet 32a overlaps one end of the magnet 36b (overlap 30 referenced r2).
This overlap serves to improve the stability of the concentric positioning of the two rings.
Figure 3 shows another variant embodiment having six, uniformly-distributed, identical magnets per ring (referenced 32a to 32f and 36a~to~36f). In this example, the magnets point so that the inner ring is automatically centered relative to the outer ring under the effect of repulsion between the .
: , -, .
- ~
~, :
2~3~
magnets in the two rings, however the magnets do not overlap, since there are suf-fi.cient rnagnets to provide sufficient stability for automatic centering.
Figure 4 is a diagrammatic section through a drive system 5 of the invention in which it can be seen that the magnets of the outer ring 32 extend over a greater height than do the magnets of the inner ring 36. This disposit:ion -together with the screening shell 34 ensures that the system is insensitive to external disturbing magnetic fields.
Figure 4 also shows that the radial plane Pi passing halfway up through the inner ring 36 is offset relative to the radial plane Pe passing halfway up through the outer ring 32, and is situatèd beneath it. In this way, a pair of oppositely directed and substantially axial forces Fe and Fi acts on the 15 rings 32 and 36. The force Fe urges the outer ring 32 upwards (when the system is oriented as shown in Figure 4), while the force Fi urges the inner ring 36 downwards.
The inner ring 36 is secured to an axial shaft 40 having an axial duct 42.
The end wall of the duct 42 is supported on the pointed tip of an axial pivot 44 which is fixed to the bottom of the housing 38 in the wall 14. Sincs the contact area between the shaft 40 and the pivot 44 is small, friction is also small and the force Fi applied to the ring 36 provides good overall 25 retention.
It can be seen in Figure l that the structure is identical for the driving ring. An axial pivot 46 terminates in a pointed tip and extends into the first chamber 10 with the bottom of the duct 28 engaging said tip when fluid flows 30 through the first chamber 10. Friction between the tip of the pivot 46 and the shaft is likewise small with the force Fe holding the assembly together.
It will thus be understood that when fluid flows through the chamber 10, the turbine 20 rotates about the pivot 46 (axis 35 AA), thereby driving the outer ring 32 which is secured thereto. Because of the repulsion force between the maynets, the inner ring 36 is caused to rotate about the pivot 44 which is accurately aligned with the pivot 46 (on axis AA).
:
, , :' ' 20~37~
The shaft 40 secured to the inner ring 36 is connected to ~;~
a counter 48.
Various conventional instruments can be seen in Figure 1 for calibration purposes and for reading the measurements 5 performed: a stroboscopic calibration wheel 50, a measuring pointer 52, and a digitcal read-out counter S4.
The magnetic drive system which is applied to a water meter in the example described is equally applicable to other types of meter and even to other types of device, e.g. a lO pumping assembly, without going beyond the ambit o~ the invention.
'~ ' :: : :
;~
, : ~ : ' : :: :: :
~.
.
Claims (10)
1/ A magnetic drive system characterized in that it comprises two concentric rings (32, 36) of magnets; same-type poles of the magnets (36a, ...) of the inner ring (36) pointing outwards from the inner ring (36), and the poles of the same type of the magnets (32a, ...) of the outer ring (32) pointing inwards from the outer ring (32), the number of magnets in each of the rings being the same and being sufficient to ensure that the inner ring (36) is automatically centered relative to the outer ring (32), rotary motion of one of the rings about its central axis (AA) causing the other ring to be driven in rotation.
2/ A magnetic drive system according to claim 1, characterized in that the magnets in each of the rings (32, 36) are uniformly distributed around the circumference of the corresponding ring, the magnets (32a, ...) of the outer ring (32) being identical to one another, and the magnets (36a, ...) of the inner ring (36) being identical to one another.
3/ A magnetic drive system according to claim 2, characterized in that the magnets have an angular extent such that the magnets of the two rings (32, 36) overlap partially.
4/ A magnetic drive system according to any one of claims 1 to 3, characterized in that each ring (32, 36) includes at least four magnets.
5/ A magnetic drive system according to any one of claims 1 to 4, characterized in that the magnets (32a, ...) of the outer ring (32) extend over a height greater than the height of the magnets (36a, ...) of the inner ring (36).
6/ A magnetic drive system according to claim 5, characterized in that the radial planes (Pi, Pe) of the inner and outer rings (36, 32) are offset so as to set up oppositely directed forces (Fi, Fe) that are substantially axial and that are applied to the rings (36, 32).
7/ A magnetic drive system according to any one of claims 1 to 6, characterized in that a screening shell (34) of magnetic material covers the outer ring (32).
8/ A meter comprising a first chamber (10) and a second chamber (12) separated by a non-magnetic sealed wall (14), the meter being characterized in that it includes a magnetic drive system according to any one of claims 1 to 7, the wall (14) forming a housing (38) containing the inner ring of magnets (36), the outer ring of magnets (32) surrounding said housing (38).
9/ A meter according to claim 8, characterized in that each ring of magnets (32, 36) is secured to a shaft (26, 40), and in that the meter further includes on either side of the bottom of the housing (38) an axial pivot terminated by a respective pointed tip (44, 46) on which the shaft (26, 40) rests.
10/ A meter according to claim 9, characterized in that the inner ring of magnets (36) is connected to a counter (48), and in that the outer ring of magnets (32) is connected to an axial turbine (20).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9106237A FR2676874B1 (en) | 1991-05-24 | 1991-05-24 | MAGNETIC DRIVE SYSTEM AND PARTICULARLY A WATER METER COMPRISING SUCH A SYSTEM. |
| FR91-06237 | 1991-05-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2068379A1 true CA2068379A1 (en) | 1992-11-25 |
Family
ID=9413064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002068379A Abandoned CA2068379A1 (en) | 1991-05-24 | 1992-05-11 | Magnetic drive system, and a meter, in particular a water meter, including such a system |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0516509A1 (en) |
| JP (1) | JPH05149764A (en) |
| KR (1) | KR920021974A (en) |
| AU (1) | AU1601592A (en) |
| BR (1) | BR9201919A (en) |
| CA (1) | CA2068379A1 (en) |
| FR (1) | FR2676874B1 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5464333A (en) * | 1993-06-24 | 1995-11-07 | Iwaki Co., Ltd. | Magnet pump with rear thrust bearing member |
| FR2715011B1 (en) * | 1994-01-13 | 1996-03-29 | Schlumberger Ind Sa | System for driving in rotation of two mechanical members by magnetic coupling and fluid meter comprising such a system. |
| FR2718526B1 (en) * | 1994-04-11 | 1997-06-06 | Landis & Gyr Tech Innovat | Water meter. |
| DE59711348D1 (en) * | 1996-04-12 | 2004-04-08 | Hans-Holger Koerner | Consumption meter with magnetic pulse generator |
| DE19723364B4 (en) * | 1997-06-04 | 2006-09-14 | Hydrometer Gmbh | Magnetic coupling for water meters with protection against external interference magnetic fields |
| FR2782419B1 (en) * | 1997-07-08 | 2001-02-23 | Ensmse | IMPROVED DEVICE FOR SYNCHRONOUS MAGNETIC COUPLINGS WITH CYLINDRICAL GAP |
| FR2766027A1 (en) * | 1997-07-08 | 1999-01-15 | Ensmse | Synchronous magnetic coupling with cylindrical airgap |
| EP2383546A1 (en) * | 2010-04-30 | 2011-11-02 | Elster GmbH | Fluid meter |
| CN107588812A (en) * | 2017-10-09 | 2018-01-16 | 南京福碧源环境技术有限公司 | A kind of type double flow meter for being available for water-softening plant salt-sucking port to use |
| CN109387251B (en) * | 2018-12-05 | 2023-12-26 | 重庆智慧水务有限公司 | Flow measuring mechanism |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1165144B (en) * | 1961-01-12 | 1964-03-12 | Siemens Ag | Drive unit |
| DE1423884B2 (en) * | 1961-08-12 | 1970-04-16 | Marx, Josef, 6503 Mainz-Kastel | Magnetic coupling for a flow meter to transmit the drive coming from the measuring mechanism |
| GB2005481A (en) * | 1977-10-01 | 1979-04-19 | United Gas Industries Ltd | Magnetic couplings |
| DE8631387U1 (en) * | 1986-11-24 | 1987-03-19 | Minol Messtechnik W. Lehmann KG, 7022 Leinfelden-Echterdingen | Measuring unit for flow meters for liquids |
| IT1230331B (en) * | 1989-07-12 | 1991-10-18 | Fedegari Autoclavi | IMPROVED MAGNETIC METHOD FOR TRANSMISSION OF MOVEMENT THROUGH WALLS OF CLOSED CONTAINERS OR CONTAINERS. |
-
1991
- 1991-05-24 FR FR9106237A patent/FR2676874B1/en not_active Expired - Fee Related
-
1992
- 1992-05-05 AU AU16015/92A patent/AU1601592A/en not_active Abandoned
- 1992-05-11 CA CA002068379A patent/CA2068379A1/en not_active Abandoned
- 1992-05-18 JP JP4124998A patent/JPH05149764A/en active Pending
- 1992-05-21 EP EP92401379A patent/EP0516509A1/en not_active Ceased
- 1992-05-21 BR BR929201919A patent/BR9201919A/en not_active Application Discontinuation
- 1992-05-23 KR KR1019920008805A patent/KR920021974A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2676874A1 (en) | 1992-11-27 |
| AU1601592A (en) | 1992-11-26 |
| EP0516509A1 (en) | 1992-12-02 |
| JPH05149764A (en) | 1993-06-15 |
| BR9201919A (en) | 1993-01-12 |
| KR920021974A (en) | 1992-12-19 |
| FR2676874B1 (en) | 1993-09-24 |
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Legal Events
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| FZDE | Dead |