WO1992015790A1

WO1992015790A1 - Device for producing a tensile force by means of a pressurized medium

Info

Publication number: WO1992015790A1
Application number: PCT/DE1992/000194
Authority: WO
Inventors: Ralph Wenzel
Original assignee: Ralph Wenzel
Priority date: 1991-03-06
Filing date: 1992-03-06
Publication date: 1992-09-17
Also published as: DE4107134A1; CA2105475A1; JPH06505326A; EP0574467A1

Abstract

A device for producing a tensile force by means of a pressurized medium comprises an expansion chamber (1), a flexible tube (3) having at least one connection (2) for the pressurized medium and a net (4) which completely surrounds the flexible tube (3) or the expansion chamber (1). The meshes (5) of the net (4) are compressed when the net is extended radially. To compensate irregularities in the flexible tube or resultant local pressure peaks which arise when the flexible tube is extended, to effectively reduce the friction, and hence the resultant abrasion or wear, between the net and the flexible tube and to ensure simple, economical manufacture, the meshes (5) are made from cords (6) which are elastic but preferably inextensible or only slightly extensible and which extend over the whole length of the flexible tube (3). Adjacent cords (6) are looped around each alternately other at predetermined distances apart so that each cord (6) follows an approximately zig-zag course and the meshes (5) so formed have an approximately elongate rhombic shape.

Description

"Device for generating a tensile force by means of pressure medium"

The invention relates to a device for generating a tensile force by means of pressure medium with an elastic hose body having an expansion chamber and at least one pressure medium connection and a network surrounding the hose body or the expansion chamber as a whole, the network having meshes that contract axially in the event of radial expansion.

Devices of the type in question have been known from practice for some time and are used, for example, in the context of robot technology for the analog design of hands, arms, legs and the like, or for their "muscle actuation". Gases or liquids, i.e. Flow media, use. Conventional and technologically complex cylinder-piston arrangements can be replaced in a simple manner by devices of the type in question, since when the expansion chamber extends radially, the network expands correspondingly radially and thereby contracts axially. This contraction takes place in the sense of the movement of a piston in a cylinder-piston arrangement, wherein when the flow medium is let out of the expansion chamber, the expansion chamber contracts radially and the network thus expands axially again.

The devices in question, known from practice, are problematic in so far as the networks or meshes formed there are characterized by fixed connections between the struts forming the meshes. The mesh size or leg length of the struts is specified there and cannot be changed. Where the struts meet, they are either knotted or - depending on the material of the struts - glued, welded or soldered. Already out for this reason, the nodes are considerably bulky, hinder handling and lead to considerable abrasive wear between the network or the nodes formed there and the hose body.

In addition, there is the particular problem that hose bodies used in devices of the type in question only rarely have one hundred percent homogeneous wall thicknesses or consistencies. Consequently, with the radial expansion of the hose body, i.e. when the hose body is filled with pressure medium, which unevenly stresses the mesh of the network, or is stressed unevenly due to the uneven expansion of the hose body. A compensation of this inhomogeneous load between individual meshes or the struts forming the meshes is not possible, so that partial load peaks can lead to destruction of the network, although the load limit of the network as a whole has not yet been exceeded.

The invention is therefore based on the object of specifying a device for generating a tensile force by means of pressure medium of the type in question, in which inhomogeneities in the tube body or resulting local stress peaks are compensated when the tube body expands. Furthermore, the friction between the network and the hose body should be effectively reduced, so that any abrasion or wear resulting therefrom is minimal. Finally, the device, in particular with regard to the network, should be simple to manufacture and thus ultimately inexpensive.

The device according to the invention for generating a tensile force by means of pressure medium achieves the above object by means of the features of patent claim 1. stretching, preferably not or only slightly stretchable but elastic strands formed. In each case, adjacent strands loop around one another at predetermined intervals in such a way that each strand runs approximately in a zigzag shape and the loops formed in this way have an approximately elongated rhombic shape.

According to the invention, it was first recognized that a simplification of the production technology and thus inexpensive configuration of the network can be achieved by forming the stitches by longitudinal strands, these strands wrapping around one another on both sides - alternately. The resulting zigzag shape, on the one hand, and the looping, which allows a relative movement between the strands, on the other hand, ensure a high flexibility or reactivity of the stitches or strands to uneven loading. In accordance with the invention, on the one hand, the manufacture of the network and thus the entire device was simplified and thereby made cheaper, on the other hand, technical disadvantages of previously known devices were at least largely eliminated.

In a particularly advantageous manner, the strands of the network loop around one another simply in the sense of a mesh fence or mesh, so that at least a slight relative movement of the strands is possible at the points of contact or lines of contact between two adjacent strands. In other words, the strands according to this advantageous embodiment are not knotted or otherwise fixed against one another, but can slide past one another within a certain range, as a result of which local load peaks of the network or the mesh can be compensated for via the strands. With regard to the design of the hose body, it is a further advantage if the network is integrated into the hose body in the sense of a reinforcement. As a result of this measure, the meshes are virtually stationary, and the strands can slide slightly against one another. As an alternative to this, the network could surround the tube body in a closely fitting or approximately form-fitting manner. In order to fix the network, this could in turn be at least slightly surrounded by an elastic encapsulant. As a result of this measure, the meshes or the points of contact or lines of contact between the strands would be virtually stationary, the certain relative movement between the. Strands is easily possible.

The investment could, for example, consist of the same material as the tube body itself, so that between the tube body and the investment - in the area between the meshes - material weft, i.e. a kind of material fusion, or at least adhesion, is present. These measures would particularly ensure that the network was fixed.

The tubular body and possibly the investment material could be made of an elastomeric material, in particular synthetic rubber or rubber. The required wall thicknesses are to be designed in the expansion chamber depending on the material used and the pressures to be applied. In the context of a special design in terms of material, the hose body and possibly the investment material are made of silicone, which results in a particularly simple production technique with regard to the hose body due to the usual silicone processing.

These are in particular to ensure the relative movement between loops of the network that wrap around one another Strands and the tube body as well as the investment material are made of materials that effectively prevent good wetting and thus good adhesion between the strands and the tube body or investment material. The possibility of an at least slight relative movement between the strands of the network and the tubular body or the investment material is ensured by this special measure. To favor the material situation or situation discussed above with regard to the resulting interfacial energies, the strands can be coated or impregnated with an agent which at least largely excludes wetting, for example with silicone oil or the like. Other coatings with the same effect are also conceivable.

With regard to a high tensile strength of the strands of the network, it is particularly advantageous if they are made of a strand, i.e. consist of several preferably twisted fibers. Likewise, the strands of the network can consist of a singular fiber, which in itself must then have the required tensile strength or tensile strength. The strands - whether stranded or singular fiber - can be made in a further advantageous manner from a high-strength plastic, preferably from nylon or the like, whereby a considerable tensile load on the network is possible. Corresponding to the pressures occurring within the tube body or the loads to be lifted or moved by the device according to the invention, the network is more or less closely meshed, the mesh or mesh diameter being designed so that the strength of the intermediate hose body is not exceeded.

To further increase the strength of the hose body or the entire device according to the invention, this could Network or the investment of the network can be covered by a second network - possibly offset in strands or meshes. This second network could be identical or similar to the first network.

With regard to the dimensioning of the network with regard to the structural size of the hose body, it is of particular advantage if the network projects beyond the hose body on both sides and at both ends - in a bound, knitted or other form - a fastening or suspension of the Device forms. Consequently, the hose body was only used for the radial expansion and thus for the axial contraction of the device according to the invention, but has no special holding or connecting function, as a result of which the hose body per se is considerably relieved.

The pressure medium connection of the device according to the invention could be attached to one end of the hose body and - optionally - serve to fasten the hose body. This pressure medium connection could be molded onto the hose body in the form of a connection nipple or the like.

If, in a further advantageous manner, one wants to physically separate the pressure medium inlet from the pressure medium outlet, for example in order to be able to carry out particularly rapid filling and subsequent ventilation of the hose body, a total of two pressure medium connections could be provided, both pressure medium connections being formed at the respective ends of the hose body could be. As already mentioned above, these two pressure medium connections could also serve to fasten the device, a corresponding tensile strength or tensile strength of the hose body material having to be ensured. As an alternative to the embodiments discussed above, the pressure medium connections could also lead into the side of the hose body and, for example, protrude unhindered through a mesh of the network. The pressure medium connections could be provided with shut-off valves, which are particularly advantageously electromagnetically actuated valves. A quick opening and closing of the valves for the sudden activation of the device according to the invention is possible.

There are various possibilities for advantageously designing and developing the teaching of the present invention. For this purpose, reference is made on the one hand to the claims subordinate to patent claim 1 and, on the other hand, to the following explanation of an exemplary embodiment of the invention with reference to the drawing. In connection with the explanation of the preferred exemplary embodiment of the invention with reference to the drawing, preferred configurations and developments of the teaching are also explained in general. In the drawing shows

1 shows a schematic illustration, partially in section, of an embodiment of an inventive device for generating a tensile force by means of pressure medium and a section along the line A-A,

2 shows a schematic illustration, partially sectioned, of the object from FIG. 1 with the expansion chamber pressurized and a section along the line BB, Fig. 3 in an enlarged detail, partially, the network of the object of FIGS. 1 and 2 and

4 shows an application example of two devices according to the invention according to FIGS. 1 to 3.

Fig. I shows an embodiment of an inventive device for generating a tensile force by means of pressure medium. This device includes an elastic hose body 3, which has an expansion chamber 1 and a pressure medium connection 2, and a network 4, which surrounds the hose body 3 or the expansion chamber 1 as a whole. The network 4 has meshes 5, which extend when the hose body 3 or of the network 4 axially contract, ie shorten in the longitudinal direction.

In the manner according to the invention, the stitches 5 are formed by elastic strands 6 which extend over the entire length of the tubular body 3 and are not or only slightly stretchable but elastic. 3 shows particularly clearly that adjacent strands 6 wrap around each other at predetermined intervals in such a way that each strand 6 runs approximately in a zigzag shape and the loops 5 formed in this way have an approximately elongated rhombic shape .

The strands 6 loop around one another simply in the sense of a mesh fence or mesh, so that at least slight relative movement of the strands 6 is possible at the points of contact or lines of contact between two adjacent strands 6. According to the section belonging to FIG. 1 along the line AA, it is at least indicated that the network 4 is integrated in the tubular body 3 or that the network 4 is at least slightly surrounded by an elastic encapsulant 7 in order to fix it the ma material of the investment 7 is identical to the material of the tube body 3.

In the exemplary embodiment selected in the figures, the strands 6 of the network 4 are each made from a singular fiber. It could also be a multi-stranded strand. According to the representations in FIGS. 1 to 3, the network 4 is of close-meshed design in accordance with the pressures occurring within the hose body 3.

Fig. 2 shows the device according to the invention in the pressurized state, i.e. in a state in which the tubular body * 3 is radially expanded, so that the meshes 5 of the network 4 - likewise radially expanded - are contracted in the longitudinal direction. As a result, a force acting along the device according to the invention can be exerted, with which, for example, a lever arm 8 according to the illustration in FIG. 4 can be applied.

In the application example selected in FIG. 4, the lever arm 8 is acted upon on both sides of a rotatable articulation 9 with a device according to the invention, so that the lever arm 8 can be both lowered and raised when subjected to force. The application example shown in FIG. 4 is used here only for the exemplary demonstration of an application of the device according to the invention to robots, namely for the actuation of robot arms, robot legs or the like.

1 and 2 further show together that the pressure medium connection 2 leads into the side of the hose body 3. The pressure medium connection 2 is provided with a shut-off valve (not shown in the figures), the shut-off valve being an electromagnetic shut-off valve. Since the strands 6 of the network 4 extend beyond the length of the hose body 3, the strands 6 present at both ends of the hose body 3, for example in a bound form, can form a suspension 10 of the device.

The production of an exemplary embodiment of the device according to the invention for generating a tensile force will be briefly discussed below. First of all, a core or the like is provided, to which, for example, silicone rubber is then applied. The core should consist of a material to which the silicone rubber does not adhere in the hardened state. In the simplest case, the core could be made of wood, for example hardwood, and brushed with or dipped in zinc stearate, stearin or another release agent. For the manufacture of the previously discussed tube body, the core could, for example, have a diameter between 10 and 15 mm and a length of approximately 20 cm. At the end, the core could taper, so that the tube body would taper accordingly.

If the pressure medium connection is to be located on the side of the hose body, a hole can be drilled in the radial direction at an angle to the axis of the core. A metal rod or the like is inserted there, for example. For a better hold, this could be tapered in the insertion area. The rod can have a diameter of approximately 3 to 5 mm and, like the core, is also coated with release agent.

After completion of the entire core, this is — as already explained above — coated with silicone rubber, for example. The final thickness or wall thickness of the hose body could be, for example, 5 to 7 mm. This layer can be applied to the core in one or more operations apply, although manual coating by multiple application is also conceivable. After a first coating of the core, a thin reinforcement could be placed on the pressure medium connection and also coated with rubber. The core should protrude from the rubber coating at both ends, so that an opening at the end is ensured. Due to the enormous elasticity of the silicone rubber, the core can later be easily removed from the tube body produced in this way.

After the tube body has completely hardened on the core, it is arranged together with the core in a stand or the like. To create the network, pulling ropes or the strands around the hose body can now be “braided” in the manner according to the invention, adjacent strands being laid around one another such that each strand runs in a zigzag shape along the hose body. To this extent, the mesh density can be varied as desired, especially since the contact points of adjacent strands are free of knots, welds or adhesions.

After each strand of the network has been interlaced once with the adjacent strand in the manner described above, the stitches can be brought into the correct position using a comb-like tool or the like, so that the tubular body - stitch row by stitch row - gradually comes along braided identical stitches. After "re-threading" the entire hose body, the strands or ropes running out at the ends of the hose body are bound together in the manner of a holder or suspension.

In the next step, the tubular body provided with the network is in turn coated with a silicone rubber mixture, so that the meshes are virtually bound in the position selected here. This drawn over the network gene layer serves to fix the network and prevents the contact points of the strands forming the stitches from slipping, so that a certain relative movement between the strands is possible, but slipping of the stitches is largely prevented.

Only after the last silicone layer has hardened is the aforementioned metal rod removed to form the pressure medium connection and the core is pressed out of the tube body as a whole. This opening is then - unless a second pressure medium connection is required here - also closed with rubber and the strands are also tied there - after removal of the core - for secure closure or to form a further suspension. Here, too, the network for fixing the mesh is coated.

The manufacturing steps described above using the example of individual production can of course also be done mechanically, i.e. perform automatically, knitting and / or knitting machines known per se being able to be used for "covering" the tube body.

Finally, it should be pointed out that the exemplary embodiment discussed above, by way of example only, serves to explain the teaching according to the invention, but is in no way intended to restrict it beyond the teaching given by the patent claims.

Claims

1. Device for generating a tensile force by means of pressure medium with an elastic hose body (3) having an expansion chamber (1) and at least one pressure medium connection (2) and a network (4) surrounding the hose body (3) or the expansion chamber (1) as a whole ), the network (4) having stitches (5) which contract axially in the case of radial expansion, characterized in that the stitches (5) extend over the entire length of the tube body (3), preferably not or only slightly bare but elastic strands (6) are formed and that each adjacent strands (6) intertwine at predetermined intervals in such a way that each strand (6) runs approximately in a zigzag shape and the stitches (5) thus formed are in have an elongated rhombic shape.

2. Device according to claim 1, characterized in that the strands (6) in the sense of a mesh fence or mesh mesh simply loop around, so that at the points of contact or lines of contact between two adjacent strands (6) an at least slight relative movement ¬ supply of strands (6) is possible.

3. Apparatus according to claim 1 or 2, characterized gekennzeich¬ net that the network (4) in the hose body (3) is integrally.

4. The device according to claim 1 or 2, characterized gekennzeich¬ net that the network (4) closely surrounds the hose body (3) or approximately form-fitting and that to fix the network (4) this by an elastic investment material ( 7) is at least slightly surrounded.

5. The device according to claim 4, characterized in that the investment material (7) consists of the same material as the tubular body (3), so that between the tubular body (3) and investment material (7) - in the area between the stitches (5) - Material closure or at least adhesion is present.

6. Device according to one of claims 1 to 5, characterized in that the hose body (3) and possibly the Ein¬ bed mass (7) made of elastomeric material, in particular synthetic rubber or rubber.

7. The device according to claim 6, characterized in that the hose body (3) and possibly the investment material (7) consists of Si¬ silicone.

8. Device according to one of claims 1 to 7, characterized in that the strands (6) of the network (4) with the material of the tube body (3) and the material of the investment material (7) poorly wet, so that between the tube body (3) or investment material (7) and the strands (6) no liability occurs and thus there is the possibility of at least a slight relative movement.

9. The device according to claim 8, characterized in that the strands (6) are coated or impregnated with a wetting agent at least largely exclude.

10. Device according to one of claims 1 to 9, characterized in that the strands (6) of the network (4) consist of a strand.

11. Device according to one of claims 1 to 9, characterized in that the strands (6) of the network (4) consist of a singular fiber.

12. The apparatus of claim 10 or 11, characterized gekenn¬ characterized in that the strands (6) made of a high-strength plastic, preferably made of nylon or the like.

13. Device according to one of claims 1 to 12, characterized in that the network (4) corresponding to the inside of the tube body (3) occurring pressures are closely meshed.

14. Device according to one of claims 1 to 13, characterized in that the network (4) or the investment material (7) of the network (4) is covered by a second network, preferably of the same type as the first network.

15. The device according to one of claims 1 to 14, characterized in that the network (4) projects on both sides over the hose body (3) and at both ends - in a bundled, knitted or other form - a fastening or suspension (10th ) of the device.

16. The device according to one of claims 1 to 15, characterized in that the pressure medium connection (2) is attached to one end of the hose body (3) and optionally serves to fasten the hose body (3).

17. Device according to one of claims 1 to 16, characterized in that a total of two pressure medium connections (2) are provided and that both pressure medium connections (2) are formed at the respective ends of the hose body (3).

18. The apparatus according to claim 17, characterized in that the two pressure medium connections (2) also serve to secure the device.

19. Device according to one of claims 1 to 15, characterized in that the or the pressure medium connections (2) laterally of the hose body (3) lead into this.

20. Device according to one of claims 1 to 19, characterized in that the or the pressure medium connections (2) are provided with shut-off valves.

21. The apparatus according to claim 20, characterized in that the shut-off valves are electromagnetically operable valves.