EP3469143B1 - Pneumatic support - Google Patents

Description

The present invention relates to a pneumatic carrier according to the preamble of claim 1 and a method for its production according to claim 10.

Pneumatic carrier of the type mentioned are known and are based on a cylindrical basic shape according to WO 01/73245 . This basic form has been further developed, among other things, into a spindle-shaped carrier according to WO 2005/007991 .

The advantage of such pneumatic carriers is their low weight and the extremely small transport volume, since the inflatable body can be folded up and the tension members can be designed as cables. A disadvantage of such pneumatic supports is that although they can carry high surface loads, i.e. they are suitable for many purposes, they are only suitable for asymmetric loads to a limited extent compared to the possible surface load, which in particular prevents use as a bridge, since a bridge over a bridge rolling axle, such as a truck, represents a particularly unfavorable case in this regard.

the Figures 1a to 1d Fig. 12 show, by way of example and diagrammatically, pneumatic supports according to the prior art, shown with exaggerated thickness for the sake of clarity. Figure 1a shows a pneumatic carrier 1 according to the WO 2005 / 042 880 with a pressure member 2, a tension member 3 and an inflatable pneumatic body 4, shown in dashed lines, arranged between pressure member 2 and tension member 3, which is inflated to operating pressure and thus keeps the pressure member 2 and the tension member 3 at a distance.

The pneumatic body 4 preferably consists of a gas-tight, flexible, essentially inextensible material which forms a cover which can be folded up for transport and which, under operating pressure, assumes a shape which is matched to the respective pneumatic carrier.

The carrier 1 is supported at its ends 6.7 by supports 8.9, where the pressure member 2 and the tension member 3 are connected to one another via a node 10.11. A planking 12 indicated schematically allows here to use the carrier 1 as a bridge.

The following thought model can explain how the carrier works:
If a load 13 acts on the planking 11 and thus on the pressure member 2, this is carried by the inflated body 4, which is under operating pressure, but which in turn rests on the tension member 3, which thus actually carries the load 13. As a result, the tension member 3 tends to deviate downwards, but this is not possible since the pressure member 2 keeps the common end nodes 10 and 11, and thus also the ends of the tension member 3, at a distance. End nodes 10, 11 denote those areas in which the compression member 2 and the tension member 3 are operatively connected to each other. Through the end nodes 10,11 force of the pressure member 2 is transmitted to the tension member 3, and vice versa, force from the tension member 3 to the pressure member 2. The end nodes 10, 11 therefore represent force application points for both the pressure member 2 and the tension member 3.

The result is that the tension member 3 is essentially only subjected to axial tension and the pressure member 2 is essentially only subjected to axial pressure, so that the tension member 3 can be designed as a cable and the pressure member 2 as a thin rod. However, a thin bar under pressure is at risk of buckling, with the result that the buckling limit of the pressure member 2 determines the load-bearing capacity of the carrier 1 .

In the case of a surface load that is distributed symmetrically over the length of the beam, as is the case with roof structures, there is a reduced risk of buckling, since buckling in a direction against the load application by the load itself reduces buckling, and buckling in the direction of the load is prevented by the support of the pressure member on the pneumatic body 4.

However, in the case of an asymmetric load, the pressure member sinks increasingly into the body 4 at the location of the load 12, and instead bulges elsewhere, with a tendency to bulge beyond the bearing surface on the body 4 and thus stand out from this, which has an increased risk of buckling and thus relevant reduced load capacity of the carrier 1 result.

For this reason, connecting elements are preferably arranged vertically (ie in the load direction and perpendicular to the longitudinal axis of the beam 1 ), designed purely as tension members 14 which connect the pressure member 2 to the tension member 3 . The tension members 14 are suitable for an asymmetrical To prevent load to a certain extent that the pressure member 2 stands out at a non-loaded location from the body 4 and thus buckles. The horizontal spacing of the tension members 14 is to be optimized by a person skilled in the art with regard to the specific case.

The connection points between the tension members 14 and the pressure member 2 as well as the tension member 3 in turn represent force application points for these elements.

Figure 1b shows a pneumatic carrier 15 according to FIG WO 2015/176 192 which also rests on supports 16,17 and has two end nodes embodied as ramp-shaped sleepers 18,19 and three pneumatic segments 20 to 22, each of the pneumatic segments having a pressure member 23 to 25 embodied, for example, as a compression bar, a compression element embodied here, for example, as a tension bar (a traction cable would also be possible) has tension member 26 to 28 and a pneumatic body 29 to 31, each pneumatic body 29 to 31 in turn keeping the respectively associated pressure member 23 to 25 and the respectively associated tension member 26 to 28 operable at a distance due to its operating pressure. Two connecting elements 32, 33 running in a zigzag manner at an angle of preferably 45° without a gap through each segment 20 to 22 (and thus without a gap through the pneumatic carrier 15 formed by the arrangement shown) form a structure that is particularly suitable for asymmetric loads and is rigid, ie under operating load, for example, relative to the carrier of Figure 1a only deflects slightly downwards from the straight (unloaded) target position.

Here, too, the connection points of the nodes 18,19 with the respective pressure member 23,25, tension member 26,28 and the connection points of the pressure members 23 to 25 and the tension members 26 to 28 with the connecting elements 32,33 form force application points in the pressure members 23 to 25 and in tension members 26 to 28.

Figure 1c shows a carrier 40, also according to the WO 2015/176 192 , Which is analogous to the carrier 15 according to Figure 1b is constructed, here has four pneumatic segments 41 to 44 and a modified longitudinal cross section, ie has a slightly convex upper side and a strongly convex lower side.

Figure 1d shows a carrier 45, also with several pneumatic segments 46 to 50, with a further modified longitudinal cross-section such that it can be loaded in the manner of a vault.

The beams 1,15,40,45 have in common the advantage that they can easily be transported dismantled and assembled on site by assembling the end nodes, compression members, tension members and any connecting elements, then inflating and pressurizing the pneumatic bodies. The disadvantage is that the carriers 1,15,40,45 increasingly warp during the pressure build-up and finally, under operating pressure but unloaded, assume an arcuate position, and only under a load their stretched target shown in FIGS. 1a to 1d -Assume position and eventually under the operational load in the case of a beam of the type in Figure 1a shown carrier 15 strong and in the case of in the manner of in the Figures 1b to 1d shown carrier 15,40,45 bend only reduced.

The curvature (ie the undesired deformation that still occurs when the pneumatic bodies 4 and 29-31 are inflated without a load) takes place in the direction of the greater curvature of the pressure member or the tension member, so that the carrier of the Figures 1a, 1b and 1d without load up and the carrier according to Figure 1c are curved downwards. As a result, the end nodes move relative to one another in the load-free state, which is undesirable.

In the Figures 1e to 1h is the curvature of the carrier 1,15,40 and 45 shown schematically on the basis of their longitudinal center lines, wherein the longitudinal center lines 55 to 58 shown in dashed lines correspond to the target position, as shown in FIGS Figures 1a to 1d is shown. The solid center lines 59 to 62 are shown extrapolated and only qualitatively according to the actual situation under operating pressure, but unloaded (ie according to the curvature). The dot-dash longitudinal center lines 58 to 61 correspond to the actual position under operating pressure and operating load, ie the load deformation, for the sake of simplicity a load not shown to relieve the figure, acting in the middle of the carrier 1, 15, 40 and 45, is assumed.

Out of Figure 1e it can be seen that the in Figure 1a illustrated pneumatic carrier 1 a comparatively large curvature and also a comparatively large deflection under load shows. The total displacement of the longitudinal centerline is too large for many applications.

Out of Figure 1f it can be seen that the in Figure 1b illustrated pneumatic support 15 shows a medium curvature and also only a small, insignificant deflection under load. The only medium curvature is due to the fact that the middle segment 21 ( Figure 1b ) is symmetrical to its longitudinal center line, i.e. essentially not warped (apart from an asymmetry that is caused, for example, by manufacturing tolerances).

Out of Figure 1g it can be seen that the in Figure 1c illustrated pneumatic support 40 shows a comparatively large curvature downwards and also a comparatively large deflection under load.

Out of Figure 1f it can be seen that the in Figure 1d illustrated pneumatic support 451 shows a comparatively large curvature, but little deflection under load.

Out of Figure 1h are the ratios discussed above for a carrier according to Figure 1d apparent.

Depending on the application, warping or deflection may or may not play a role - warping is unfavorable, for example, in the case of a bridge, which should be as rigid as possible. So it is particularly disadvantageous if a bridge formed from beams according to Figure 1b although it would be extraordinarily rigid and therefore particularly suitable for its use, but due to the curvature at the ends it has to be negotiated steeply and then up to its target position (line 18 from Figure 1f ) behaves spongy / yielding. The advantage of the flexural rigidity is only reduced to the full.

Analogously, depending on the application, this also applies to other pneumatic carriers, for example according to Figures 1a to 1h .

Accordingly, the object of the present invention is to provide a pneumatic support which only reduces or avoids the phenomenon of buckling.

The object is solved according to the characterizing features of claims 1 and 10.

The fact that the pneumatic body has formations extending between adjacent force application points, which protrude outwards beyond a straight connection between the adjacent force application points, results in a pressure distribution in the pneumatic body (or in the pneumatic bodies of the segments of a pneumatic carrier having several segments ) which counteracts the curvature and thus reduces or prevents it.

The invention is explained in more detail below with reference to the figures.

Figur 1a bis 1d

schematisch pneumatische Träger gemäss dem Stand der Technik,

Figur 1e bis 1h

schematisch die Verkrümmung der pneumatischen Träger unter lastfreiem Betriebsdruck, unter Betriebsdruck und Betriebslast sowie in einer Soll - Lage ohne Verkrümmung,

Figur 2

schematisch einen erfindungsgemäss ausgebildeten pneumatischen Träger, und

It shows:

Figure 1a to 1d

schematic pneumatic carrier according to the prior art,

Figure 1e to 1h

Schematically the curvature of the pneumatic support under no-load operating pressure, under operating pressure and operating load and in a target position without distortion,

figure 2

schematically a pneumatic carrier designed according to the invention, and

figure 2 shows an embodiment of a pneumatic carrier 70 according to the invention, which rests on the carrier 15 of FIG Figure 1b is constructed. The segments 71 to 73 can be seen, with the segments 71 and 73 being modified and the segment 72 having the same structure as the segment 21 of the carrier 15 ( Figure 1b ) is equivalent to.

It should be noted at this point that, in principle, any type of pneumatic carrier can be modified according to the invention if and to the extent that it exhibits the phenomenon of curvature.

The pressure rods 74 to 76 are shown, as well as the tension elements designed as tension cables 77, 79 and the tension rod 78 of the segments 71 to 73. Also shown are the compared to the embodiment of FIG Figure 1b unchanged connecting elements 33,34, which stiffen the pneumatic carrier 70 in the case of the operating load. Also unchanged from the embodiment of FIG Figure 1b is the pneumatic body 81, while the pneumatic Bodies 80, 82 are modified according to the invention as described below.

the figure 2 12 further shows the force application points 83, 84 and 85 present in the segments 71, 73, the force application points 83 connecting the connecting element 33, the sleeper 18 and the traction cable 77 to one another and thus introducing the corresponding forces into the traction cable 77. The force application points 85 connect the pull rod 78, the connecting element 33 or 34 and the pull cable 77, as a result of which the corresponding forces are introduced into the pull cable 77. The force application points 84 connect the traction cable 77 to the connecting elements 32 , 33 and introduce the corresponding forces into the traction cable 77 . Between adjacent force application points 83,84 or 84,84 and 84,85 80,82 formations 86 to 89 are provided in the pneumatic bodies, which according to the embodiment of figure 2 are provided on the tension member side.

According to the invention, these formations 86 to 89 result in an equilibrium of forces in the pneumatic bodies 80, 82 due to the operating pressure, in which there is essentially no deformation of the pneumatic body due to the operating pressure—in contrast to the prior art. The formations 86 to 89 are advantageous, and preferably as in the figure 2 shown, arc-shaped, most preferably arc-shaped, and extend from a force application point 83 to 85 to the adjacent force application point 84.

In this case, the protrusions 86 to 89 more preferably have a height above the connecting line between the force application points 83 to 85 delimiting them of 10 to 15% of the distance between these force application points 83 to 85 . The Applicant has found that such a height is already effective in reducing the undesired curvature.

Finally, more preferably, the tension member 77, 79 is operatively connected to the pneumatic body 80, 82 only at the location of the force application points 83 to 85, so that the tension member can extend straight between the force application points 83 to 85 and does not follow the contour of the pneumatic body 80, 82 or The contour of the formations 86 to 89 must follow, which under operating pressure leads to a shortening of the distance between the force application points 83,85 and then to a more complicated design of the entire segment 71,73 in relation to the pressure rod 74,76, the pressure body 80 .82, the traction cable 77.79 and the contour of the formations 86 to 89, which is very difficult to calculate and would therefore have to be determined by trials.

The result is that, according to the preferred embodiment shown in the figure, a pneumatic carrier (with one or more pneumatic bodies that are asymmetrical in the longitudinal direction) in which under operating pressure but unloaded, its side having the pressure member is at least partially curved in an arc and its side having the tension member Page is designed such that its force application points lie essentially on a straight line.

At this point it should be noted that, of course, the configuration of the pneumatic support according to figure 2 can be modified, for example by omitting the central segment, so that the side having the pressure member is continuously curved in an arcuate manner. In a simulation, the applicant has determined the curvature of a 38 m long pneumatic beam for an operating load of 4.5 t with a continuously curved pressure member and straight tension member (such a configuration should be particularly convenient to set up in the field, since the tension member or the underside of the pneumatic support then rests on the floor). However, the curvature leads to a "hump" of the beam with a height of about 1 meter, the tension member in the middle of the beam lifts off the ground at about the same height. However, the pneumatic carrier provided with formations according to the invention, which otherwise has the same configuration as the carrier of the prior art, was essentially free of the curvature, which was only in the range of approx. 10 cm.

In summary, according to the invention there is provided a pneumatic support having one (or more) pneumatically pressurizable pneumatic body which, under operating pressure, operatively spaced a compression member extending substantially along its length and a tension member also extending substantially along its length, wherein in end regions of the pressure member and the tension member, forces are introduced into these at force introduction points, and connecting elements are provided between the pressure member and the tension member, which also introduce forces into the pressure member and the tension member at force introduction points, the pneumatic body having formations extending between adjacent force introduction points , the after protrude beyond a straight connection between the adjacent force application points.

As mentioned above, the pneumatic carrier preferably has a flexible envelope (namely the pneumatic body - or, in the case of several segments, several pneumatic bodies with several flexible envelopes) whose cutting pattern determines the shape of the carrier under operating pressure, such that form the formations in a predetermined contour.

Since at least one connecting element is preferably provided in the pneumatic carrier, which extends in a zigzag shape through the entire length of the pneumatic body, and which particularly preferably, as mentioned above, runs at an angle of 45° to the intended load direction (in the case of a bridge i.e. 45° to the horizontal). For this reason, the adjacent force application points are at different distances from one another when the distance between the pressure member and tension member changes, as is evident from the embodiment according to FIG figure 2 is the case in the segments 71, 73 or, in general, in the case of pressure bodies which are designed asymmetrically over a length. As a result, in turn, the protrusions 86 to 89 have different heights, since this height is preferably determined in relation to the distance between the associated force application points.

Since the calculation for this is complex, the height of the formations is determined iteratively in a particularly simple manner: In a first step, the height is determined at 10 to 15% of the distance between the assigned (i.e. adjacent) force application points. After that, the pneumatic support can still have an unwanted residual curvature, so that in a second step the height of the protrusions is further increased by 30 - 50% (with an initial 10% increase, the resulting height would then be between 13 and 15% of the distance between the neighboring force application points). This iterative process converges very quickly for most configurations of a pneumatic beam to be determined by a person skilled in the specific case, but can be continued without further ado until the curvature essentially disappears or no further improvement occurs for the intended use of the beam.

In detail, it results that according to the invention a method is provided in which arc-shaped, preferably arc-shaped, Formations are provided, the height of which is 10 to 15% of the distance between the associated force application points.

Thus, the structure of a pneumatic carrier according to the invention is preferably designed such that one (or more) formations have a height above the connecting line between the force application points that delimit them of 10 to 15% of the distance between these force application points.

Then, if the iterative method is used, the pneumatic beam designed according to the invention is built and the pneumatic body of the beam is brought to operating pressure and it is checked whether there is any distortion of the beam that persists compared to the intended shape, and if so, the height of selected formations is checked 30-50% increased. Normally, the person skilled in the art will increase all the formations equally, but in the case of a special shape of the pneumatic body in question, he can only change selected formations, for example through tests).

Finally, if desired for the intended use of the pneumatic beam, the iterative process can be continued, i.e., iteratively increasing the height of the protuberances until further increase does not further improve the curvature of the unloaded beam.

As a result, the invention provides a method for manufacturing a pneumatic support, in which the shape of the pneumatic support intended during operation and the location of the force application points and then the curvature to be expected under operating pressure but without operating load are determined in advance, and then formations on the The inside of the curvature of the pneumatic carrier can be provided, which extend from force application point to force application point via a connecting line between associated force application points to the outside.

Claims (13)

1. A pneumatic support (70) having at least one pneumatic body (80-82) which can be placed pneumatically under pressure and which, under operating pressure, operatively keeps at a distance apart a compression member (74-76) which extends substantially over its length and a tension member (77-79) which likewise extends substantially over its length, wherein forces are introduced at force introduction points (83-85) in end regions of the compression member (74-76) and the tension member (77-79) into said members and wherein connecting elements (32, 33) are provided between the compression member (74-76) and the tension member (77-79) and introduce forces into the compression member (74-76) and the tension member (77-79) likewise at force introduction points (83-85),
   characterised in that
   the pneumatic body (80, 82) has formations (86-89) which extend between adjacent force introduction points (83-85) and which project outwardly beyond a rectilinear connection between the adjacent force introduction points (83-85).
2. The pneumatic body according to Claim 1, wherein the formations are provided on the side of the tension member (77-79).
3. The pneumatic support according to Claim 1, wherein the formations (86-89) are designed such that the support (70) curves less during buildup of the operating pressure in the pneumatic body (80, 82) than is the case in a similarly designed pneumatic support without formations, and wherein the deflection of the support (70) resulting from the curvature is preferably less than 30%, very preferably less than 10%, of the deflection without formations.
4. The pneumatic support according to Claim 1, wherein at least one connecting element (32, 33) is provided, which extends in a zigzag manner continuously through the entire length of the pneumatic body (80-82).
5. The pneumatic support according to Claim 1, wherein the pneumatic support (70) has a flexible sleeve, the pattern of which defines the shape of the support (70) under operating pressure such that the formations (86-89) are formed in a predefined contour.
6. The pneumatic support according to Claim 1, wherein the formations (86-89) are arcuate, preferably circular arc-shaped, and extend from one force introduction point (83-85) to the adjacent force introduction point (83-85).
7. The pneumatic support according to Claim 1 or 6, wherein the formation (86-89) has a height above the connection line between the force introduction points (83-85) delimiting it of 10 to 15% of the spacing of these force introduction points (83-85).
8. The pneumatic support according to Claim 1, wherein, when the support (70) is under operating pressure but load-free, the side thereof with the compression member (74, 76) is at least partially curved in an arcuate manner, and the side thereof with the tension member (77, 79) is designed such that the force introduction points (83-85) thereof lie substantially on a straight line.
9. The pneumatic support according to Claim 1, wherein the tension member (77-79) is operatively connected to the pneumatic body (80-82) only at the location of the force introduction points (83-85).
10. A method for producing a pneumatic support according to Claim 1,
    characterised in that
    the intended shape of the pneumatic support (70) during operation and the location of the force introduction points (83-85) 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 (70) are provided, said formations extending outwardly from force introduction point (83-85) to force introduction point (83-85) via a connection line between associated force introduction points (83-85).
11. The method according to Claim 10, wherein arcuate formations (86-89) are provided, the height of which is 10 to 15% of the spacing of the associated force introduction points (83-85).
12. The method according to Claim 10, wherein the pneumatic body (80-82) of the support (70) is brought to operating pressure and checked for the presence of a curvature of the support (70) relative to the intended shape, and in the positive case the height of selected formations (86-89) is increased by 30-50%.
13. The method according to Claim 12, wherein the height of the formations (86-89) is increased iteratively until a further increase does not produce any further improvement in the curvature of the unloaded support (70) .

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