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Publication numberUS3279388 A
Publication typeGrant
Publication dateOct 18, 1966
Filing dateSep 25, 1964
Priority dateSep 30, 1963
Publication numberUS 3279388 A, US 3279388A, US-A-3279388, US3279388 A, US3279388A
InventorsRoudaut Philippe R L
Original AssigneeRoudaut Philippe R L
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Semi-rotary magnetic device
US 3279388 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

oct. 1s, 1966 Filed Sept. 25, 1964 P. R. L. ROUDAUT SEMI-ROTARY MAGNETIC DEVICE 5 Sheets-Sheet l Oct. 18, 1966 P. R. L ROUDAUT 3,279,388

SEMI-ROTARY MAGNETI C DEVI CE Filed Sept. 25, 1964 3 Sheets-Sheet 2 Irv/amiral Oct. 18, 1966 P. R. L. ROUDAUT 3,279,388 SEMI-ROTARY MAGNETIC DEVICE Filed Sept. 25, 1964 3 Sheets-Sheet 5 United States Patent O 3,279,388 SEMI-ROTARY MAGNETIC DEVICE Philippe R. L. Roudaut, 54 Rue Lecuyer, Sotteville-les-Rouen, Seine Maritime, France Filed Sept. 25, 1964, Ser. No. 399,143 Claims priority, application France, Sept. 30, 1963, 949,106; Apr. 6, 1964, 969,897 19 Claims. (Cl. 103-148) Th-is invention relates to a semi-rotary magnetic device for driving rotary machines, more particularly tubular diaphragm pumps.

These machines lare of course used preferably for the conveyance of corrosive fluids, .their mechanism being isolated from the intake Iand delivery chambers by one or more diaphragms which are deformed either intermittently or continuously to product variations in the volume of the chambers so that the liquid is drawn in and then delivered.

Submersed-rotor pumps are also used which are magnetically coupled or integral with a submersed-rotor motor, generally of the centrifugal type, in order to climinate the disadvantages of glands or packings.

The disadvantages :of the former is .that the .behaviour of the diaphragm constitutes a weak point of their design because in the event of a breakage, puncture or quite simply porosity, the pumped liquid invades the motor compartment and damages the mechanism at a speed depending upon the corrosive nature of the iluid, and this results sometimes in very expensive maintenance changes, whereas these charges should be limited to the replacement of the diaphragm. Safety systems can be iitted, for example diaphragms in several thicknesses, but these only defer the problem, particularly if the breakage is abrupt; or else probes may be provided which give a warning although, inevitably, after the event and hence they only limit the above disadvantages.

The latter systems do not have this disadvantage but they are suitable only for clear liquids because any suspended matter, whether or not abrasive, becomes deposited in the clearances between the rotor and stator and this results in a prolonged interruption of the magnetic ux,

blockage and hence stoppage of the machine.

The present device ena-bles the -advantages of the two systems Ito be combined without their disadvantages.

The present invention .is 'applied preferably to tubular diaphragm pumps, i.e., pumps ofan elongated shape comprising one or more cavities communicating lat one of their ends with an inlet aperture and Iat the other end with an outlet aperture for the fluid that is to be pumped, such cav-ities lbeing formed by -a exi'ble tubular diaphragm contained in a tubular body.

rI'lie invention relates more particularly to 1a magnetic device for producing periodic deformation of the diaphragm to effect the required displacement of the cavities from one end of the pump to the other.

According to one embodiment of the invention, the diaphragm is of flexible material and comprises preferably the narrowest possible rings lof magnetic material distributed over its length, means being provided to subject such rings to magnetic flux, whose passage provides displacement of such rings and hence lthe required deformation of the diaphragm. v

These means may be permanent magnets or other magnets which rotate in relation to the annular space containing the diaphragm. These magnets, which act on the rings, are so disposed Ithat radial movements occur with offsetting on said rings, the rotated force is absorbed by the semi-ilexible partitions generally provided in such machines or by contact in the case of constructions without partitions, thus preventing :any continu-ous friction by rotation yof the parts n the pump liquid.

3,279,388 Patented Oct. 18, 1966 The magnets are separated mechanically from the rings by a tubular rigid or semi-rigid partition permeable to the magnetic ilux, so that there is an auxiliary chamber between the diaphragm and the rotary elements; this chamber can receive any type of uid whether or not compre'ssible, clear and preferably compatible with the liquid which is being conveyed. Also, such fluid can be used for cooling or heating the diaphragm and as a thermal screen for the rotary part.

lIn the event of damage of the diaphragm the conveyed liquid would pass from the deformable chamber to the auxiliary chamber between the diaphragm and the partition so that no leakage would occur towards the mechanical rotating parts and even less to the exterior of the pump. Since any clear fluid contained in the 'auxiliary chamber is compatibile with the delivered iluid, n-o accidents can take place in the event of its passage to the installation provided with the pump. The pumped liquid passes beneath the rings, short-circuits the magnetic flux and Ithus causes the pump delivery to move towards Zero smoothly, the eccentrically obtained in the movement of the rings reducing as the bearing surfaces on the rigid tube become clogged,

This system also eliminates the disadvantage of volumetric pumps for which it is also intended, namely, the need for a relief pressure valve in the event of accidental blockage of the delivery; in fact, at the magnet zone the diaphragm may be considered `as urged by .a sp-ring whose calibration is simply the magnetic attraction. This pressure can be varied voluntraily by moving the magnets away from the attracted elements by some means in order to sh1ortcircuit rthe lines of force of the eld. For the practical embodiment, the number of magnets used will depend von the required pressure.

The delivery of lthe machine can also be controlled during operation, Without lany variation of the speed of rotation, by this magnetic system.

In this type of machine the delivery depends on the eccentricity and also on the pitch produced. It is therefore necessary only to vary the pitch of the magnet support by auxiliary means, which in this case may advantageously .be a spring Whose calibration is variable during operation.

The delivery and pressure may be combined `to give a required characteristic curve.

The accidental reversal of the direction of rotation of the pump driving motor generally is of course known to have harmful repercussions since the direction of iiow of the pumped liquid depends on the said direction of rotation. If the driving motor is outside the driven pump it is easy to check the direction of rotation and obviate such a fault immediately. But if the motor is of the submerged rotor type, in particular, control means must be provided to check that the direction of rotation of the machine is the required direction.

The means most frequently employed without intertering with sealing is an observation hatch but it cannot be used for unclear liquid (by definition) and since it is impossible to say that a liquid will remain clear it is impossible to say that this means will always be of use.

The device according to the present invention enables the direction of flow in pumps equipped with such a device to be made relatively independent of the direction of rotation of the driving motor.

AIf the motor is considered to have a given direction of rotation, the direction of flow of the fluid depends on the ydirection in which the helix formed by the magnet support or by the magnets themselves is wound; thus if this element is cancelled out for example by a movement of translation (which is preferable in this case) and then replaced by another element with an opposite pitch, the direction of ow is reversed without the direction of rotation of the motor having change. A given direction of flow for the fluid can therefore be maintained irrespective of the direction of rotation of the motor and in fact without the latter direction even being known.

This system may also be retained for a pump which is required to be reversible in operation as in certain laboratory work. Control in this case may be manual or controlled by the installation itself and the delivery can pass through zero before reversal; for example, in accordance with the variation principle indicated above, in the case of magnets in operation while others must come into operation in inverse proportion, either directly or via their supports.

According to another feature of the invention and in `order more particularly to reduce the size of the device to the minimum, the volume available for installation of the magnets is utilised to the maximum by making the magnets in the form of split rings mounted coaxially of the rotary shaft and uniformly offset from one another about the axis of the shaft so as to produce the required helical magnetic field.

Advantageously, installation is obtained by means of non-magnetic supports concentric of the magnets and fitting between the ends of the latter.

Means are preferably provided to vary the pitch of the helical field, so as to reduce the starting torque or control delivery during operation.

rI`he invention is illustrated by way of example in the accompanying drawings, in which:y

FIGURE l is a diagrammatic longitudinal section of a device according to the invention;

FIGURE 2 is also a diagrammatic longitudinal section of a modification;v

FIGURE 3 is an axial half-section of another modification, and

FIGURE 4 is a cross-section on the line IV-IV in FIGURE 3.

In the embodiment shown in FIG. 1, the device cornprises a tubular element 1 of cylindrical shape and of a material permeable to magnetic flux and fitted at its ends to the base of the pump equipped with the system, sealing being provided directly by the diaphragm M- of the pump in question.

U-section rings 2 .are clamped or stuck inside the.

diaphragm and the arms of the U face inwards. These rings are of a material sensitive to the magnetic flux, for example soft iron.

The shaft 3 forms the magnetic assembly support and is provided with a bushing 4 to support a magnet S to which are connected two pole elements 6 and 7 for north and south respectively, which are helieally coiled on a helical element 8 which is impermeable to the magnetic flux and which keeps the pole elements 6 and 7 rigidly spaced. The end of these elements is fitted to the face of a semi-flexible cup 9 which acts as a hydraulic piston slidable on the shaft 3 and rotatable to a certain extent.

The rings 2 are attracted helically along the helix formed by the elements 6, 7 and 8 through the tube 1 so that the diaphragm looks like a coarse pitch screw.

When the shaft 3 to which the elements 6, 7 and 8 are connected is rotated, the rings and hence the diaphragm are kept in contact with the element 1 magnetically at the zone of the parts 6 and 7 so that the cavities formed between the pump body and the diaphragm undergo continuous and regular deformations so that streams of liquid can be progressively forced from the intake to the delivery for a given direction of rotation.

Since the force of the magnets is perpendicular to their faces, such force is used integrally and there is only a practically negligible torque tending to rotate the diaphragm and this is absorbed by the semi-flexible partitions of the diaphragm connecting the latter to the pump Ibody C or possibly by friction if there are no such partitions.

As a result of this system any incident to the diaphragm will not affect the mechanical rotating part of the machine thus equipped, since the element 1 prevents any leak.

Of course, permanent magnets have been propose-d for reasons of simplicity but means such as electromagnets may 'be used for powerful machines.

In the embodiment shown in FIG. l, the delivery of the pump provided with such a system can also be varied during operation. That surface of the piston 9 which is remote from the pole elements is subjected to the pressure of a servo liquid which can move it along the shaft axis as far as the magnet support 4, thus reducing the pitch of the pole elements and their support 6, 7 `and S and hence the volume of the cavities and therefore the rate of delivery of the pump without any variation in the speed of rotation.

The rotation of this piston cup is not stopped, so that under .the force resulting from the increased compression on the pole elements-which react like a calibrated spring-the cup can describe a certain angle so that it does not offer any resistance to the pole elements as theirl resilience varies.

In the case of pumps which are driven by motors of the submerged rotor type, FIG. 2 illustrates an embodiment of a iiow varying and reversing system.

In this case the rings 2 are rigidly connected, for example are stuck, to the flexible pump diaphragm M and while they again have a U-section, the arms of the U face outwards.

The hollow shaft 3 is used as a support for the magnetic system, which is similar to that described hereinbefore but which acts towards the axis of rotation through the tube 1. This system is substantially duplicated however, the second part being with an opposite pitch.

It comprises the four pole elements 6a, 7a, and 6b, 7b which are respectively mounted on the uxeimpermeable elements Sa or 8b which are coiled in opposite pitches and which at one end abut a piston 9 serving as a support for the magnets Sa and Sb, and at the other end when necessary--on compressionthey abut aV circlip 10a and 10b inside the suppor-ting shaft 3.

With this embodiment, the direction of flow of the pump liquid can be reversed by hydraulic application to one face of the piston 9, the diaphragm Ithen being urged by the magnetic system coiled in the opposite direction to that previously in operation, without it being necessary to change the direction of rotation of the motor, this being possible due to the fact that elements 8a and 8b are of an opposite pitch, as discussed above.

FIGS, 3 and 4 show the essential elements of the device described with reference to FIGS. 1 and 2, namely the diaphragm M outside the tubular element 1 in which rotates the shaft 3 fitted in the frame P.

' The ends of the diaphragm M have peripheral beads 11 by means of which the diaphragm is supported on the ends 12 of the tubular element 1 and on the ared surfaces 13 of the frame P covered by extensions 14 of the diaphragm. The uid for delivery arrives at the tube 15 4and leaves by the tube 16.

Between the beads 11 the diaphragm M is mounted on free rings 17 of magnetic material which are fitted between peripheral ribs 1S for guiding the elment 1 by means of much narrower rings 19 and 20 than -the rings 17, said rings 19 and 20 being partially embedded in the inner wall of the diaphragm; the rings 19, which are slightlyv thicker than the rings 20, are disposed substantially symmetrically with respect to the rings 17, which they surround with very little clearance, while the rings 20 straddle the adjacent edges of two consecutive rings 17, with respect to which they have a fairly considerable clearance. This ring system gives a very uniform helical deformation of the diaphragm with only a small number of magnetic rings 17. The rings 19 and 20 may be of metal or of a fairly rigid synthetic material.

The end rings 17a are bored to a smaller dimension than the other rings 17, in order to reduce deformation of the diaphragm near its securing means.

The guide ribs 18 enable the thickness of the tubular element 1 to be reduced to a minimum in order to reduce magnetic losses.

Inside the tubular element 1 the shaft 3 bears magnets 21 in the form of split rings mounted on supports 22, for example of bronze and having a projection 23 engaging between the poles of the magnets (FIG. 4). Supports 22 are strung on .the shaft 3 between a shoulder 24 and a stop washer 25 which is locked by a split ring 26 (FIG. 3). T-hese elements are axially fixed by balls 27 mounted in peripheral grooves 28 of the shaft 3.

Diametrically opposite the projection 23, for example, the supports 22 are formed with a recess 29 housing a block 30 of rubber or similar flexible material. The various blocks 30 are drilled for the passage of a coarse-pitch helical spring 31 one end 31a of which is fitted in an aperture in the shoulder 24 and the other end 31b of which is secured to an annular piston 32 which is slidable and rotatable on the corresponding end of the shaft 3 in a cylindrical chamber 33 formed in the frame P. Ducts 34 and 35 provide for the intake and discharge of pressure fluid on either side of the piston 32 so that the latter can move in its cylinder 33 to vary the pitch of the spring 31 and hence the angular offset 21.

The projection 23 on the supports 22 also has a flat 36 at its outer portion so that a helical tool of magnetic material can be introduced between the rotor 21, 22 and the tubular element 1 in order to close the flux on assembly. This tool is then withdrawn on commissioning. It prevents any sticking due to uncontrolled attraction during installation.

The device operates like the device described wi-th reference to FIGS. 1 and 2 but on starting up all the magnets are in contact with the corresponding rings 17 so that the pressure outside the diaphragm tends to oppose the rotation. Because of their resilient mounting on the shaft 3 the magnets 21 undergo an angular offset when the pump rotates. After starting, the magnets return to their operative positionY under the return action of the spring 31 whose deformation enabled the delivery and hence the power on starting to be reduced.

During operation the general pitch can be varied by means of the piston 32 by the application of pressure liquid via the ducts 34 or 35.

I claim:

v1. A semi-rotary magnetic device for driving tubular diaphragm pumps, comprising rin-gs of magnetic material distributed along the length of -the diaphragm and means for subjecting said rings to variable magnetic flux in order to produce the required deformation of the diaphragm.

2. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm.

3. A device according to claim 1 wherein the said means comprises at least one magnet which rotates with respect to the sytem formed .by the rings and the diaphragm, and which acts on the rings through the agency of pole elements disposed al-ong helixes coaxial with the diaphragm.

4. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm, and which acts on the rings through the agency of pole elemen-ts disposed along helixes coaxial with the diaphragm, a tubular partition permeable to the magnetic ux separating the magnets an-d the pole elements from the rings.

5. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm, and which acts on the rings through the agency of pole elements -disposed along helixes coaxial with the diaphragm, means being provided to vary .the pitch of the pole elements.

6. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with lrespect to the system formed by the rings and the diaphrag-m, and which acts on the rings through .the agency of pole elements disposed along helixes coaxial with the diaphragm, and wherein the pole elements are flexible and one of their ends is connected to a ring which forms a piston 'between the tubular partition and the drive shaft for .the said lpole elements, means being provided to apply a pressure uid to the ring piston in order to vary the pitch of the pole elements.

7. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with respect to the system formed Iby the rings and the diaphragm, and which acts lon the rings through the agency of pole elements disposed along helixes coaxial with the diaphragm, and wherein the pole ele-ments are exible and one of their ends is connected to a ring which forms a piston between the tubular partition and the drive shaft for the said pole elements, means being provided to apply a pressure fluid to the ring piston in order to vary the pitch of the pole elements, and wherein the ring piston bears magnets on its two surfaces, the said magnets corresponding to opposite-pitch helical pole elements, ducts for the passage of hydraulic fluid being provided on either side of the ring in order to permit operation of one or :other of the sets of pole elements in order to reverse the direction of operation of the pump.

8. A device according to claim 1 wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm, and which acts on the rings through the agency of pole elements disposed along helixes coaxial with the diaphragm, and wherein the pole elements are flexible and one of their ends is connected to a ring which forms a .piston between the tubular partition and the drive shaft for the said .pole elements, means -being provided to apply a pressure uid to the ring piston in order to vary the pitch of the pole elements, and wherein the ring piston Ibears magnets yon its two surfaces, the said magnets corresponding to oppositepitch helical pole elements,

' ducts for the passage of hydraulic fluid being provided on either side of the ring in order to permit ope-ration of one or other of the sets of pole elements in order to reverse the direction of operation of the pump, the said magnets being on the inside with respect to the diaphragm.

`9. A device accor-ding to claim 1 wherein the said means comprise at least yone magnet which rota-tes with respect to lthe system formed by the rings and the diaphragm, and which acts on the rings through the agency of pole elements disposed along helixes coaxial with the diaphragm, and wherein the pole elements are iiexible and one of their ends is connected to a ring which fonms a piston lbetween the tubular partition and the drive shaft for the said pole elements, means bein-g provided to apply a pressure fluid to the ring piston in order to vary the pitch of the pole elements, and wherein the ring pist-on bears magnets on its two surfaces, the said magnets corresponding to -oppositepitch helical pole elements, ducts for the passa-ge of hydraulic fluid being provided Ion either side of the ring in order to permit operation of one or other of the sets of pole elements in order to reverse the direction of operation of the pump, the said magnets being on the -outside with respect to the diaphragm.

10. A device according to claim 1, wherein the said means comprise at least one magnet which rotates with respect to the system formed -by the rings and the diaphragm, the magnets being in the form of split rings mounted coaxially of the rotary shaft and regularly offset from one another about the axis of said shaft.

11. A device according toclaim 1, wherein the said means comprise at least one magnet which rotates with 3,279, ses.

respect to the system formed by the rings and the diaphragm, the magnets being in thefonm of split rings mounted coaxially of the rotary shaft and regularly offset from one another about the axis of said shaft and means being provided for varying the amount of oifset of the magnets.

12. A -device according to claim 1, wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm, the magnets being in the form of split rings mounted coaxially of 4the rotary shaft and regularly oftset from one another about the axis of said shaft, the magnets being mounted on supports having a projection tted between their poles.

13. A device according to claim 1, wherein the said ymeans comprise at least one magnet which rotates with respect to the system formed by the rings an-d the diaphragm, the magnets being in the fonm of split rings mounted coaxially of the rotary shaft and regularly offset from sone another about the axis of said shaft, the magnets being mounted on supports having a .projection itted between their poles and the said supports being mounted loosely on lthe shaft and connected to one an-l other and t-o the latter by a resilient device.

14. A device according to claim L1, wherein the said means comprise at least one magnet which rotates with respect to the system formed by the rings and the diaphragm, the magnets being in the form of split rings mounted coaxially of the rotary shaft and regularly offset from one another about the axis of said shaft, the Ina-g- .nets being mounted on su-pzports having a projection itted between their poles and the said supports being mounted loosely on the shaft and connected to one another and to the latter by a resilient `device comprising a spring one end of which is secured to the shaft which is connected to the supports yby flexible blocks, and the free end of which is connected to a piston which can be moved in a chamber at the end lof the shaft, ducts being provided on either side of the piston for moving the latter in the chamber by means of a compressed fluid.

15. A device according to claim 1, wherein the said means comprise at least one magnet which rotates with respect to the system formed 'by -the rings and the diaphrag-m, the magnets being in the form of split rings mounted coaxially of the rotary shaft and regularly offset from one another about -the axis of said shaft, the magnets being mounted on supports havin-g a lprojection fitted between their poles, the said supports being mounted on the shaft by means of rings of balls.

`16. A device according to claim y1 wherein the said means comprise at least one magnet which rotates with respect t-o the system formed by the rings and the diaphr'agrn, and which acts on the rings through the agency of .pole elements disposed along heliXes coaxial with the diaphragm, a tubular partition permeable t-o the magnetic iiux separating the magnets and the pole elements from the rings, `and the said magnetic rings being guided by ribs .provided on the tubular element.

17. A semi-'rotary magnetic device for driving tubular diaphragm pumps, comprising rings of magnetic material distributed along the length of the diaphragm and means f-or subjecting said rings to variable magnetic flux in order to produce the 'required deformation of the diaphragm, the said diaphragm bearing on the magnetic rings through the agency of rings of which there are one more than twice the number of magnetic rings, some of these rings surrounding the corresponding magnetic rin-g without kany appreciable clearance and others straddling the ends of two contiguous magnetic rings with some clearance.

18. A semi-rotary magnetic device for driving tubular diaphragm pumps, comprising rings of magnetic material distributed along the length of the diaphragm and means for subjecting said rings to variable magnetic ux in order to :produce the required defonmation of the diaphragm, the said diaphragm bearing on the magnetic rings through the agency of rings of which there are one more than twice the number of magnetic rings, some of -these rings surrounding the corresponding magnetic ring Without any appreciable clearance and others straddling the ends of two contiguous magnetic rings with some clearance, the end magnetic rings having a smaller bore than the others.

19. A semi-notary magnetic device for driving tubular diaphragm pumps, comprising rings of magnetic material distributed along the length of the diaphragm and means for subjecting said rings to variable magnetic flux in order to produce -the required deformation of the diaphragm, the said ldiaphragm bearing on the body of the device through the agency of wide beads and flared extensions.

References Cited by the Examiner 5/1952 France. MARK NEWMAN, Primm-y Examiner. W. L. FREEH, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1922196 *Mar 17, 1932Aug 15, 1933Nordberg Manufacturing CoPump
US2278821 *Oct 14, 1940Apr 7, 1942Louise Gunnila Violet BennetFluid engine
US2888877 *Apr 19, 1956Jun 2, 1959Ohio Commw Eng CoApparatus for pumping
US3089425 *Jan 30, 1961May 14, 1963Thompson Ramo Wooidridge IncMagnetic pump
AT175516B * Title not available
FR1008458A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5286176 *May 6, 1993Feb 15, 1994The United States Of America As Represented By The Secretary Of The NavyElectromagnetic pump
US5660529 *Dec 6, 1994Aug 26, 1997Mcgaw, Inc.Linear peristaltic pump with reshaping fingers interdigitated with pumping elements
US5846064 *Sep 1, 1995Dec 8, 1998Metameric LimitedPeristaltic pump
US5888052 *Aug 26, 1997Mar 30, 1999Mcgraw, Inc.Linear peristaltic pump with reshaping fingers intedigitated with pumping elements
US6234773Oct 12, 1998May 22, 2001B-Braun Medical, Inc.Linear peristaltic pump with reshaping fingers interdigitated with pumping elements
US20160090979 *May 20, 2014Mar 31, 2016Hanning Elektro-Werke Gmbh & Co. KgPump arrangement
Classifications
U.S. Classification417/412, 418/158, 417/420, 418/48, 418/153
International ClassificationF04B43/08, F04B43/00
Cooperative ClassificationF04B43/082
European ClassificationF04B43/08B