Pneumatic structural element

Abstract

The pneumatic support has a pneumatic body which can be placed pneumatically under pressure and which, under operating pressure, operationally keeps at a distance apart a compression member which extends substantially over its length and a tension member which likewise extends substantially over its length, wherein forces are introduced at force introduction points in end regions of the compression member and the tension member into said members and wherein connecting elements are provided between the compression member and the tension member and introduce forces into the compression member and the tension member likewise at force introduction points, wherein, furthermore, the pneumatic body has formations which extend between adjacent force introduction points and which project outwardly beyond a rectilinear connection between the adjacent force introduction points. As a result, undesired distortion of the support under operating pressure, but without operating load, is avoided.

Claims

1. A pneumatic support comprising: a pneumatic body which can be placed pneumatically under pressure and which, under an operating pressure, operatively keeps a compression member which extends substantially over a length of the pneumatic body a distance apart from a tension member which likewise extends substantially over the length of the pneumatic body, wherein forces are introduced at force introduction points in end regions of the compression member and the tension member into said compression member and tension member connecting elements are provided between the compression member and the tension member that introduce forces into the compression member and the tension member likewise at force introduction points, wherein, the pneumatic body has formations which extend between adjacent force introduction points and which project outwardly beyond a rectilinear connection between the adjacent force introduction points.

2. The pneumatic body according to claim 1, wherein the formations are provided on the side of the tension member.

3. The pneumatic support according to claim 1, wherein: the formations are designed such that the pneumatic support curves less during buildup of the operating pressure in the pneumatic body than if formations were not present, and the deflection of the support resulting from the curvature is preferably less than 30 of the deflection without formations.

4. The pneumatic support according to claim 1, wherein the connecting element extends in a zigzag manner continuously through an entire length of the pneumatic body.

5. The pneumatic support according to claim 1, wherein: the pneumatic support has a flexible sleeve, and the pattern of the flexible sleeve defines the shape of the support under operating pressure such that the formations are formed in a predefined contour.

6. The pneumatic support according to claim 1, wherein the formations are arcuate and extend from one force introduction point to the adjacent force introduction point.

7. The pneumatic support according to claim 1, wherein the formation has a height above the connection line between the force introduction points delimiting the height of 10 to 15% of the spacing of these force introduction points.

8. The pneumatic support according to claim 1, wherein, when the pneumatic support is under operating pressure but load-free, the side thereof with the compression member is at least partially curved in an arcuate manner, and the side thereof with the tension member is designed such that the force introduction points thereof lie substantially on a straight line.

9. The pneumatic support according to claim 1, wherein the tension member is operatively connected to the pneumatic body only at the location of the force introduction points.

10. A method for producing a pneumatic support according to claim 1, wherein an intended shape of the pneumatic support during operation and a location of the force introduction points are defined and then the curvature to be expected under operating pressure but without operating load is defined, and then formations on the inside of the curve of the pneumatic support are provided, said formations extending outwardly from force introduction point to force introduction point via a connecting line between associated force introduction points.

11. The method according to claim 10, wherein arcuate formations are provided, the height of which is 10 to 15% of the spacing of the associated force introduction points.

12. The method according to claim 10, wherein the pneumatic body of the pneumatic support is brought to operating pressure and checked for the presence of a curvature of the support relative to the intended shape, and in the positive case the height of selected formations is increased by 30-50%.

13. The method according to claim 12, wherein the height of the formations is increased iteratively until a further increase does not produce any further improvement in the curvature of the unloaded support.

Description

(1) In the figures:

(2) FIGS. 1a to 1d schematically show pneumatic supports according to the prior art,

(3) FIGS. 1e to 1h schematically show the distortion of the pneumatic supports under load-free operating pressure, under operating pressure and operating load, and in a desired position without distortion,

(4) FIG. 2 schematically shows a pneumatic support designed according to the invention.

(5) FIG. 2 shows an embodiment according to the invention of a pneumatic support 70 which is constructed analogously to the support 15 having three segments 20 to 22 as shown in FIG. 1b. The segments 71 to 73 can be seen, the segments 71 and 73 being modified and the segment 72 corresponding in structure to the segment 21 of the support 15 (FIG. 1b).

(6) It should be noted at this point that in principle any type of pneumatic support exhibiting the phenomenon of distortion can be modified according to the invention.

(7) Shown are the compression rods 74 to 76 and the tension elements in the form of tension cables 77, 79 and the tension rod 78 of the segments 71 to 73. Also shown are the connecting elements 33, 34 which are unchanged in comparison with the embodiment of FIG. 1b and reinforce the pneumatic support 70 under operating load. Likewise unchanged in comparison with the embodiment of FIG. 1b is the pneumatic body 81, while the pneumatic bodies 80, 82 are modified according to the invention, as described below.

(8) FIG. 2 also shows the force introduction points 83, 84 and 85 present in the segments 71, 73, the force introduction points 83 connecting the connecting element 33, the sill 18 and the tension cable 77 to one another and thus introducing the corresponding forces into the tension cable 77. The force introduction points 85 connect the tension rod 78, the connecting element 33 or 34 and the tension cable 77, as a result of which the corresponding forces are introduced into the tension cable 77. The force introduction points 84 connect the tension cable 77 to the connecting elements 32, 33 and introduce the corresponding forces into the tension cable 77. Formations 86 to 89 are provided between adjacent force introduction points 83, 84 or 84, 84 and 84, 85 in the pneumatic bodies 80, 82, said formations being provided on the side of the tension member in the embodiment of FIG. 2.

(9) Thanks to these formations 86 to 89, a force equilibrium is produced according to the invention in the pneumatic bodies 80, 82 by the operating pressure, with which force equilibrium deformation of the pneumatic body by the operating pressure is substantially omitted, in contrast to the prior art. Formations 86 to 89 are advantageously, and preferably as shown in FIG. 2, arcuate, very preferably circular arc-shaped, and extend from one force introduction point 83 to 85 to the adjacent force introduction point 84.

(10) Further preferably, the formations 86 to 89 have a height above the connection line between the force introduction points 83 to 85 delimiting them of 10 to 15% of the spacing of these force introduction points 83 to 85. The applicant has found that such a height already effectively prevents the undesirable distortion.

(11) Finally, the tension member 77, 79 is further preferably operatively connected to the pneumatic body 80, 82 only at the location of the force introduction points 83 to 85, so that the tension member between the force introduction points 83 to 85 can extend rectilinearly and do not have to follow the contour of the pneumatic body 80, 82 or of the contour of the formations 86 to 89, which results in a shortening of the spacing of the force introduction points 83, 85 under operating pressure, and then results in a more complicated design of the whole segment 71, 73 in relation to the compression rod 74, 76, the pressure body 80, 82, the tension cable 77, 79 and the contour of the formations 86 to 89, which is very complex to calculate and therefore would have to be determined by experiments as well.

(12) According to the preferred embodiment shown in the figure, a pneumatic support (having one or more asymmetrical pneumatic bodies in the longitudinal direction) is produced, in which, when under operating pressure but load-free, the side thereof with the compression member is at least partially curved in an arcuate manner, and the side thereof with the tension member is designed such that the force introduction points thereof lie substantially on a straight line.

(13) It should be mentioned at this point that the configuration of the pneumatic support according to FIG. 2 can of course be modified, for example by omitting the central segment, so that the side with the compression member is curved in a continuously arcuate manner. In a simulation, the applicant determined the distortion of a 38 m-long pneumatic support for an operating load of 4.5 t with a continuously arcuate compression member and a straight tension member (such a configuration should be particularly favourable for construction in the field, since the tension member or the lower face of the pneumatic support then lies on the ground). However, the distortion results in a hump in the support with a height of approx. 1 metre, the tension member in the centre of the support lifting off from the ground to approximately the same height. However, the pneumatic support provided with formations according to the invention and otherwise having the same configuration as the support from the prior art was substantially free of distortion, which was only in the region of approx. 10 cm.

(14) In summary, a pneumatic support is produced according to the invention having a (or multiple) pneumatic body which can be placed pneumatically under pressure and which, under operating pressure, operationally keeps at a distance apart a compression member which extends substantially over its length and a tension member which likewise extends substantially over its length, wherein forces are introduced at force introduction points in end regions of the compression member and the tension member into said members and wherein connecting elements are provided between the compression member and the tension member and introduce forces into the compression member and the tension member likewise at force introduction points, wherein the pneumatic body has formations which extend between adjacent force introduction points and which project outwardly beyond a rectilinear connection between the adjacent force introduction points.

(15) As already mentioned above, the pneumatic support preferably has a flexible sleeve (specifically the pneumatic body or, in the case of multiple segments, multiple pneumatic bodies having multiple flexible sleeves), the pattern of which defines the shape of the support under operating pressure such that the formations are formed in a predefined contour.

(16) There is preferably at least one connecting element in the pneumatic support, said connecting element extending in a zigzag manner continuously through the entire length of the pneumatic body and particularly preferably running, as mentioned above, at an angle of 45 to the intended loading direction (therefore, 45 to the horizontal in the case of a bridge). Therefore, the adjacent force introduction points have different spacings from one another when the spacing of the compression member and the tension member changes, as is the case in the embodiment according to FIG. 2 in the segments 71, 73 or generally in pressure bodies formed asymmetrically over a length. The formations 86 to 89 thereby have different heights, since this height is preferably defined in relation to the spacing of the associated force introduction points.

(17) In a particularly simple manner, the height of the formations is defined iteratively, since the calculation for this is complex: In a first step, the height is defined at 10 to 15% of the spacing of the associated (i.e. adjacent) force introduction points. Then, the pneumatic support can still have an undesirable residual distortion, and therefore the height of the formations is increased further by 30-50% in a second step (with an initial 10% increase, the resulting height would then be between 13 and 15% of the spacing of the adjacent force introduction points). With most configurations of a pneumatic support to be defined for the specific case by a person skilled in the art, this iterative method converges very rapidly but can easily be continued until the distortion substantially disappears or no further improvement occurs for the intended use of the support.

(18) Specifically, a method is provided according to the invention with which arcuate, preferably circular arc-shaped, formations are preferably provided in a pneumatic support, the height of which formations being 10 to 15% of the spacing of the associated force introduction points.

(19) Therefore, the structure of a pneumatic support according to the invention is preferably designed such that a (or multiple) formation has a height above the connecting line between the force introduction points delimiting them of 10 to 15% of the spacing of these force introduction points.

(20) The pneumatic support designed according to the invention is then constructed for the case of the application of the iterative method, and the pneumatic body of the support is brought to operating pressure and checked for the presence of a persistent distortion of the support relative to the intended shape, and in the positive case the height of selected formations is increased by 30-50%. Usually, a person skilled in the art will increase all the formations equally but can change only selected formations, for example by experimentation, if the affected pneumatic body has a particular shape.

(21) Finally, if desired for the intended use of the pneumatic support, the iterative method can be continued, i.e. the height of the formations can be increased iteratively until a further increase does not produce a further improvement in the curvature of the unloaded support.

(22) As a result, a method is provided according to the invention for producing a pneumatic support, in which the shape of the pneumatic support during operation and the location of the force introduction points are defined in advance and then the distortion to be expected under operating pressure but without operating load is defined, and then formations on the inside of the curve of the pneumatic support are provided, said formations extending outwardly from force introduction point to force introduction point via a connecting line between associated force introduction points.