Expansible chamber devices – Collapsible chamber wall portion – Wall portion formed of flexible material
Reexamination Certificate
1999-01-25
2001-01-30
Look, Edward K. (Department: 3745)
Expansible chamber devices
Collapsible chamber wall portion
Wall portion formed of flexible material
Reexamination Certificate
active
06178872
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention resides in a worm-like operating mechanism actuated by pneumatic or hydraulic pressure fluids for lifting, fixing, grasping and moving objects. The mechanism is stretchable and/or pivotable in any direction. It includes pressurized fluid-operated actuators, which automatically return to their rest position when the pressurized fluid is released. Such mechanisms are suitable for forming robot arms, artificial limbs or controllable movable parts for medical instruments.
Operating mechanisms known presently for those applications are relatively complicated and expensive and provide only for limited movability or relatively small force transmission.
DE 39 18 955 A1 discloses mechanism corresponding in principle to a muscle. It includes a balloon-like container consisting of a flexible skin with a pump for pumping a fluid into, or out of, the balloon-like container. The balloon is surrounded by a net, which can be extended lengthwise up to a maximum length at which point the balloon enclosed by the net completely contracted and has no internal volume. When the balloon is filled to its maximum volume the ends of the net are pulled together to a minimum distance. The net then firmly engages the balloon and prevents a destructive further expansion. With this arrangement, a joint-like elbow can be operated, however, movement is limited to one degree of freedom.
Actuators of the artificial muscle type are described in GB 2 240 083 A. They include channel-like elements which can assume any spatial state between a total collapse (zero volume) and a fully expanded state (maximum volume). They include desired fold areas. By filling or emptying the channels the desired volume states can be obtained. By arranging these elements in series, arm- or tentacle-like structures can be formed. The channels are enclosed by, or embedded in, support foils which limit volume expansion.
WO 90/15697 shows plug-like shapes, which can be operated by pressurized fluid such that stretch or bending motions are produced. Channel-like structures are connected for this purpose to other foils such that, upon filling, the whole structure assumes a predetermined shape. The movement of the structure however has only a single degree of freedom starting with a folded limp structure and leading to an expanded taut structure and vice versa.
DE 196 17 852 A1 discloses a method of making fluid operated miniature manipulators employing expandable pocket structures comprising two foils disposed on top of each other. The foils are welded together along a line and include a supply passage for the admission and the discharge of fluid. They can assume any volume between zero and a maximum volume. The various designs illustrated however do not permit any tilting motion either, that is, they have only one degree of freedom.
It is the object of the present invention to provide an operating mechanism for generating spatial tilt and linear movements which mechanism is capable of generating large movements and large forces.
SUMMARY OF THE INVENTION
In a worm-like operating mechanism having hydraulic or pneumatic actuators arranged around a central axis, the actuators include serially arranged bags disposed in connection with one another and being folded meander-like and having fluid passages for supplying fluid under pressure to, or evacuating, the actuators individually, so that the operating mechanism can be lengthened or shortened or bent in any direction.
The actuators may consist of torus-shaped meander-like joined bags which may be held together by retaining and support rings to form the actuating mechanism. The actuators may consist of two foils, which are welded together along a given line selected to provide any desired hose, bag or pocket shape. The shape that can be generated by such attached bags or pockets is highly variable although only simple manufacturing processes are required to achieve that result. The support elements, which are disposed in the actuator folds for containing the bags can be simple rings, which may have a certain elasticity. However, they may also consist of the material of which the support elements are made, which are disposed in the outer folds for maintaining the meander shape and which are relatively stiff. The support rings may be omitted if the adjacent pillows of the respective actuator are interconnected in a point or line-like fashion (cemented or welded) but they may be retained for containing the bags. Also, adjacent bags may be welded or cemented together along a line so that the outer support rings which circumferentially engage the bags at the outer folds can be omitted.
Another actuator design includes a folded hose structure that is, it includes bags joined in series such that bellows structures, not meander-like structures are formed.
To facilitate return movement of the actuators or the whole drive mechanism elastic return elements are utilized. The return elements may be disposed in lumina. They may include a hose or screw springs arranged centrally within, or along the free corner areas between, the actuators, along the discs or through the discs. In this case, there is provided an additional cohesion structure for the operating mechanism.
The operating mechanism further may be anchored at its proximal end. This may be achieved by a flange by which it can be screwed to a support or by a bayonet lock arrangement. In narrow spaces or channels, the drive mechanism may also include pneumatically or hydraulically expandable bags which are arranged in star-like annular form or an annular bag engaging at the proximal end a wall. For stability reasons, two adjacent rings of such bags would be advantageous, but this depends on the intended application.
The operating mechanism can be anchored at one end, but it may also be anchored at the other end if there is such an arrangement also at the distal end, If anchoring arrangements are provided at both ends of the actuating mechanism, a wormor caterpillar-like movement can be obtained. To this end, first only the proximal operating bag is expanded and, pressing against the adjacent wall, the mechanism is lengthened and anchored at the distal end. The proximal bag is then emptied and the mechanism is pulled toward the distal end. For a return movement, the process is reversed. As a result, advance movement in curved channels or pipes is possible.
The operating mechanism can be employed as a lifting apparatus, or used for operating a joint, a grasping or a retaining apparatus and it can be modified for use as a moving mechanism, as a robot arm, or it can be employed in an artificial limb, ssssfor example in an arm, hand, or leg prosthesis. The mechanism can bend in any direction and be returned to a straight position. In addition to the bending movement, an elongation of the operating mechanism can also be achieved.
With the inch worm-like drive mechanism, a basic operating element is provided which provides for high movability with small bending radii and large bending angles. Because of the particular materials needed for its construction, the mechanism is very light-weight, but is capable of generating or transmitting large forces. The design is simple and cost-effective since the materials are inexpensive and their processing for forming the actuators and the assembly of the respective operating mechanism is simple. Inspite of its simplicity, the operating mechanism can easily be adapted to various fields of application. It may be constructed, if necessary, without the use of any metal parts. Because it is easy to manufacture and has wide applications, the mechanism is economical and, because of its capabilities, it is technically very attractive.
The invention will be described below in greater detail on the basis of the accompanying drawings:
REFERENCES:
patent: 4784042 (1988-11-01), Paynter
Bach Klaus J.
Forschungszentrum Karlsruhe GmbH
Lazo Thomas E.
Look Edward K.
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