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(11) | EP 0 430 981 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
FLUID-DRIVEN ACTUATORS FLUID-BETÄTIGTE AKTUATOREN ACTUATEURS HYDRAULIQUES |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
BACKGROUND OF THE INVENTION
[0001] This invention relates to fluid-driven actuator devices. It is particularly but not exclusively intended for use in a system in which one or more packages is to be ejected from a container.
[0002] The conversion of fluid pressure and motion to linear displacement by means of a piston or bellows is well known. A piston-based device requires a rigid cylinder within which the piston is caused to move by fluid pressure, and the length of the cylinder must correspond to the displacement or stroke of the piston. If the piston is used to eject a package from a container at a substantial velocity, either the stroke is short, the cylinder is short and the ejection shock relatively high; or the stroke is made longer and the shock is reduced, but appreciable packaging space is lost because a larger rigid cylinder is required. If a device essentially comprising a bellows is used as an ejector, unless the displacement path of the bellows during its extension is defined by some rigid guide such as a surrounding tube, the body of the bellows will tend to distort away from the ideal because the system cannot remain symmetrical and stable.
[0003] Another form of actuator may be based on a flexible sac, which may be stored in a deflated state requiring relatively little packaging space, and expanded by inflation to provide the actuation movement. Known devices perform in an unpredictable manner during inflation of the sac. Furthermore, if rapid inflation is required the configuration of the sac is further complicated by transient phenomena associated with fluid flow into the sac and the nature of any external load. When fully inflated, however, the sac will adopt a shape determined either by the walls of the sac or by container into which it has been expanded, or by some combination of the two.
SUMMARY OF THE INVENTION
[0005] A document disclosing features corresponding to those in the precharacterising portions of the independent claims is GB-A-2055427.
[0006] In one embodiment of the invention a fluid-driven actuator comprises an inflatable sac having a first portion for providing a working surface and a second, stowed portion; and a container which contains the said second portion of said sac and includes fluid pressure inlet means for communicating fluid pressure to the interior of said sac; and is characterised by a bulkhead and guide means defining with said bulkhead a narrow opening separating said first and second portions of said sac and allowing said first portion of the sac to draw the second portion of the sac through the opening as the sac is inflated.
[0007] In another embodiment of the invention a fluid-driven actuator comprises an inflatable sac having a first portion for providing a working surface and a second, stowed portion; and is characterised by a support for said first portion of the sac, said support including a fluid pressure inlet for communicating fluid pressure to the interior of said first portion of said sac to cause inflation thereof, and a member movable relative to said support, said movable member including a bulkhead for engagement by said working surface of the sac, said bulkhead including a narrow opening separating said first portion of the sac from said second portion and defining the working surface of the sac, the inflation of said sac causing said working surface to engage said bulkhead, to move said member away from said support and to draw said second portion through said narrow opening.
[0008] Two specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 2 is a simplified illustration of successive stages in the inflation cycle of the first embodiment of the invention;
[0011] Figure 3 is a detailed cross-sectional representation of the first embodiment of the invention showing an applied load;
[0012] Figure 4 is a schematic cross-sectional representation of a further embodiment of the invention;
[0013] Figure 5 is a detailed cross-sectional representation of the second embodiment of the invention showing an applied load.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] Referring to Figure 1, which is a sectional view of a circular assembly, the fluid-driven actuator comprises a relatively strong sac 1. The sac is generally flexible. Preferably it comprises a systematically folded part 7 and a working part, which is effectively a surface 4 and which may be flexible but could be rigid or partially rigid. The sac is contained behind a bulkhead 2 and located by a guide 3. The guide 3 comprises a flanged disc which has a central aperture 3a. The working part of the sac at any time is separated from the folded part by a relatively narrow opening 6. The sac is sealingly secured to a cylindrical container 20, which has an inlet port 5. The guide 3 is supported by means not shown.
[0015] When a source of fluid pressure is applied at an inlet port 5 to the container in the direction of the arrow, the working face 4 is forced beyond the bulkhead, and as it moves, it draws the folded portions of the sac through the narrow opening 6 between bulkhead 2 and the guide 3. It will be readily appreciated that in this way, the internal pressure in the sac tends to urge the wall of the sac towards the bulkhead opening, whilst the working section of the sac is maintained fully inflated. Reaction pressures are therefore referred to the bulkhead and the fluid source, whilst the working portion of the sac, being fully inflated has a configuration defined by the container and the sac design.
[0016] Figure 2 illustrates the way in which a relatively long stroke may be achieved from a compact stored state. In practice, the shape of the sac would be distorted by the restriction imposed by the container.
[0017] Figure 3 is a detailed illustration of a particular embodiment according to Figure 1. This embodiment is used as an ejector for a device 8 supported by a hod 9, which rests on the working face 4 of the sac 1. A fluid inlet fitting 5 fits sealingly into a central aperture 3a of a guide 3, and comprises a channel section support 10 and a threaded conduit 11.
[0018] From the foregoing, it will be appreciated that although a circular device has been described, cross-sections of alternative shape may be employed, with different methods of folding . or otherwise stowing the sac. Similarly, alternative locations for fluid entry may be chosen.
[0019] It should also be noted that in these descriptions 'working face', 'bulkhead' and 'guide' are relative terms, and a system may be configured in which the 'working face' is effectively stationary, and in which the 'bulkhead' constitutes a container for the folded portion of the sac and is made to move under pressure. A separate guide structure may not be necessary for some configurations. Although the working face is shown in Figures 1 and 2 as a portion of the sac, it may be a separate member which is wholly or partly sealed to the wall or face of the sac.
[0020] Another embodiment is illustrated schematically in Figure 4. A strong flexible sac-like container 1 of square or rectangular cross-section is attached at one end to a fixed flange 12. The bulk of the sac 16 is suitably folded into a ribbon form and passes through an aperture formed in a moveable member 13. This is most conveniently an elongate slot 15. The bulk of the sac beyond the slot is further compacted, and stored ready for use, by folding regularly in a zig-zag form, for example.
[0021] When a source of fluid pressure is applied at an inlet port 17 as indicated by the arrow, a sac cavity 14 is inflated to apply a moving force to member 13. As this member moves away from the flange 12, the folded sac is withdrawn continuously from the storage compartment through the slot and inflated in such a way as to maintain a force on the member 13. It will be appreciated that the sac-like container is, in fact, a tube, and the folded end need not be sealed.
[0022] Figure 5 is a detailed illustration of a particular embodiment of the rectangular assembly according to Figure 4. This embodiment is used as an ejector for a device 8 supported by a hod 9. The hod is supported on an adjustable gap plate which comprises a moving member 13. A fluid inlet fitting 17 comprises a channel section support 10 and a threaded conduit 18 which has a flange 12. The flange fits sealingly with a sac 1.
[0023] The flexible sac in the foregoing description may be constructed from any flexible or acceptably fluid-tight material, provided that the geometry of the sac is sufficiently well defined for its purpose at full working pressures. Rubberised canvas and the like are particularly suitable, whilst other plastics and ductile metals, singly or in combination, are practicable to satisfy the wide range of dimensions, pressures, cross-sectional forms, and applications for which this invention is suitable.
1. A fluid-driven actuator comprising: an inflatable sac (1) having a first portion for
providing a working surface and a second, stowed portion; and a container (2) which
contains the said second portion of said sac and includes fluid pressure inlet means
(5) for communicating fluid pressure to the interior of said sac; characterised by
a bulkhead (2) and guide means (3) defining with said bulkhead a narrow opening separating
said first and second portions of said sac and allowing said first portion of the
sac to draw the second portion of the sac through the opening as the sac is inflated.
2. An actuator according to claim 1 wherein said stowed portion is compactly folded within
said container.
3. An actuator according to claim 1 wherein said guide means is disposed inside the sac.
4. An actuator according to claim 1 and further comprising a movable member positioned
to be engaged by said working surface and to be moved by said working surface.
5. A fluid-driven actuator comprising: an inflatable sac (1) having a first portion for
providing a working surface and a second, stowed portion (16); characterised by a
support (10) for said first portion of the sac, said support including a fluid pressure
inlet (17) for communicating fluid pressure to the interior of said first portion
of said sac to cause inflation thereof, and a member (9) movable relative to said
support, said movable member including a bulkhead (13) for engagement by said working
surface of the sac, said bulkhead including a narrow opening (15) separating said
first portion of the sac from said second portion and defining the working surface
of the sac, the inflation of said sac causing said working surface to engage said
bulkhead, to move said member away from said support and to draw said second portion
(16) through said narrow opening.
6. An actuator according to claim 5 wherein said first portion (14) of said sac is sealed
to said support.
7. An actuator according to claim 5 wherein said member comprises a hod (9) supporting
a device for ejection, said hod being spaced from the bulkhead and said second portion
of the sac being disposed between the hod and the bulkhead (13).
8. An actuator according to claim 7 wherein said second portion is folded.
1. Fluidbetätigter Aktuator aufweisend: einen aufblasbaren Beutel (1) mit einem ersten
Abschnitt zum Bereitstllhen einer Angriffsfläche und einem zweiten gestauten Abschnitt;
und einen Behälter (2), der den zweiten Abschnitt des Beutels enthält und eine Fluiddruck-Einlaßvorrichtung
(5) zum Weitergeben von Fluiddruck an das Innere des Beutels aufweist;
gekennzeichnet durch
eine Scheidewand (2) und Führungsmittel (3), die mit der Scheidewand eine schmale Öffnung begrenzen, die den ersten und zweiten Abschnitt des Beutels voneinander trennt und zuläßt, daß der erste Abschnitt des Beutels den zweiten Abschnitt des Beutels durch die Öffnung hindurchzieht, wenn der Beutel aufgeblasen wird.
gekennzeichnet durch
eine Scheidewand (2) und Führungsmittel (3), die mit der Scheidewand eine schmale Öffnung begrenzen, die den ersten und zweiten Abschnitt des Beutels voneinander trennt und zuläßt, daß der erste Abschnitt des Beutels den zweiten Abschnitt des Beutels durch die Öffnung hindurchzieht, wenn der Beutel aufgeblasen wird.
2. Aktuator nach Anspruch 1, wobei der gestaute Abschnitt im Innern des Behälters klein
zusammengefaltet ist.
3. Aktuator nach Anspruch 1, wobei das Führungsmittel im Beutelinnern angeordnet ist.
4. Aktuator nach Anspruch 1 und weiter aufweisend ein bewegliches Element, das so angeordnet
ist, daß die Angriffsfläche damit in Eingriff gehen und das bewegliche Element verschieben
kann.
5. Fluidbetätigter Aktuator aufweisend: einen aufblasbaren Beutel (1) mit einem ersten
Abschnitt zum Bereitstellen einer Angriffsfläche und einem zweiten gestauten Abschnitt
(16); gekennzeichnet durch einen Träger (10) für den ersten Abschnitt des Beutels,
wobei der Träger einen Fluiddruckeinlaß (17) zum Weitergeben von Fluiddruck an das
Innere des ersten Abschnitts des Beutels aufweist, um dessen Aufblasen zu bewirken,
und ein bezüglich des Trägers bewegliches Element (9) mit einer Scheidewand (13),
mit der die Angriffsfläche des Beutels in Eingriff gehen kann, wobei die Scheidewand
eine schmale Öffnung (15) aufweist, die den ersten Abschnitt des Beutels von dem zweiten
Abschnitt trennt und die Angriffsfläche des Beutels begrenzt, wobei das Aufblasen
des Beutels die Angriffsfläche dazu veranlaßt, mit der Scheidewand in Eingriff zu
gehen, um das Element von dem Träger wegzubewegen and den zweiten Abschnitt (16) durch
die schmale Öffnung hindurchzuziehen.
6. Aktuator nach Anspruch 5, wobei der erste Abschnitt (14) des Beutels druckdicht mit
dem Träger verbunden ist.
7. Aktuator nach Anspruch 5, wobei das Element eine Tragmulde (9) aufweist, die eine
Auswurfvorrichtung abstützt und von der Scheidewand und dem zweiten Abschnitt des
zwischen der Tragmulde und der Scheidewand (13) angeordneten Beutels beabstandet ist.
8. Aktuator nach Anspruch 7, wobei der zweite Abschnitt zusammengefaltet ist.
1. Actionneur commandé par fluide comprenant : un sac gonflable (1) ayant une première
partie fournissant une surface motrice et une seconde partie, repliée ; et un conteneur
(2) qui contient ladite seconde partie dudit sac et qui comprend un moyen d'entrée
de pression de fluide (5) pour communiquer une pression de fluide à l'intérieur dudit
sac ; caractérisé par une cloison de séparation (2) et un moyen de guidage (3) définissant
à l'aide de ladite cloison de séparation une ouverture étroite séparant lesdites première
et seconde parties dudit sac et permettant que ladite première partie du sac tire
la seconde partie du sac à travers l'ouverture lorsque le sac se gonfle.
2. Actionneur selon la revendication 1, dans lequel ladite partie repliée est pliée de
manière compacte à l'intérieur dudit conteneur.
3. Actionneur selon la revendication 1, dans lequel ledit moyen de guidage est disposé
à l'intérieur du sac.
4. Actionneur selon la revendication 1, et comprenant en outre, un élément mobile placé
pour être contacté par ladite surface motrice et pour être déplacé par ladite surface
motrice.
5. Actionneur commandé par fluide comprenant : un sac gonflable (1) ayant une première
partie fournissant une surface motrice et une seconde partie, repliée (16) ; caractérisé
par un support (10) pour ladite première partie du sac, ledit support incluant une
entrée de pression de fluide (17) pour communiquer une pression de fluide à l'intérieur
de ladite première partie dudit sac pour provoquer son gonflage, et un élément (9)
mobile par rapport audit support, ledit élément mobile incluant une cloison de séparation
(13) destinée à être contactée par ladite surface motrice du sac, ladite cloison de
séparation comportant une ouverture étroite (15) séparant ladite première partie du
sac de ladite seconde partie et définissant la surface motrice du sac, le gonflage
dudit sac amenant ladite surface motrice à contacter ladite cloison de séparation,
pour écarter ledit élément dudit support et pour tirer ladite seconde partie (16)
à travers ladite ouverture étroite.
6. Actionneur selon la revendication 5, dans lequel ladite première partie (14) est raccordée
de façon étanche audit support.
7. Actionneur selon la revendication 5, dans lequel ledit élément comprend une auge (9)
supportant un dispositif pour éjection, ladite auge étant espacée de la cloison de
séparation, et ladite seconde partie du sac étant disposée entre l'auge et la cloison
de séparation (13).
8. Actionneur selon la revendication 7, dans lequel ladite seconde partie est pliée.