Title of Invention	BRIDGING DEVICE FOR AN EXPANSION JOINT IN A STRUCTURE FIT FOR TRAFFIC
Abstract	The invention relates to a bridging device for an expansion joint (4) in a structure fit for traffic, said expansion joint being placed between an abutment (2) and a superstructure (3). A number of cross-members (5) that bridge the joint gap extend between the abutment and the superstructure and are supported on the abutment and on the superstructure. A multitude of slats (7) extending in a longitudinal direction of the gap are placed between the abutment and superstructure and are each supported on at least one portion of the cross-members. The distance of the slats from one another is controlled by spring devices to which the relevant slats are connected. The individual spring devices provide different controlling forces according to their arrangement inside the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction of the joint.

Title of Invention

BRIDGING DEVICE FOR AN EXPANSION JOINT IN A STRUCTURE FIT FOR TRAFFIC

Abstract

The invention relates to a bridging device for an expansion joint (4) in a structure fit for traffic, said expansion joint being placed between an abutment (2) and a superstructure (3). A number of cross-members (5) that bridge the joint gap extend between the abutment and the superstructure and are supported on the abutment and on the superstructure. A multitude of slats (7) extending in a longitudinal direction of the gap are placed between the abutment and superstructure and are each supported on at least one portion of the cross-members. The distance of the slats from one another is controlled by spring devices to which the relevant slats are connected. The individual spring devices provide different controlling forces according to their arrangement inside the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction of the joint.

Full Text	WO 2006/074892 Al BRIDGING DEVICE FOR AN EXPANSION JOINT IN A STRUCTURE FIT FOR TRAFFIC The instant invention relates to a bridging device for an expansion joint fit for traffic, said expansion joint being placed between an abutment and a superstructure comprising the following features: a number of cross-members that bridge the joint gap extend between the abutment and the superstructure and are supported on the abutment and on the superstructure; a multitude of slats extending in a longitudinal direction of the joint are placed between the abutment and the superstructure and are each supported on at least one portion of the cross-members; the distance of the slats from one another is controlled by spring devices to which the relevant slats are connected. Bridging devices of the type specified above, as they are used in particular in bridge building, are known in different designs. Possibilities for variations thereby exist, for example, with regard to the positioning of the cross-members in that one side thereof can be fixedly clamped (see, e.g., DE 19607593 Al) or in that they can be supported so as to slide on the abutment as well as on the superstructure (see, e.g., DE 3201751 C2). The slats can be supported so as to slide on all of the cross-members or individual slats or all of the slats are fixedly connected with assigned cross-members that, in each case, are supported so as to slide on the superstructure as well as on the abutment, whereby, in this case, a sliding support of the slats on the remaining cross-members is possible, but not imperative. The spring devices that are connected in serj.es in the form of a control chain are thereby supposed to provide for the most even distances of the - 2 - slats to one another. Such a control of the slat distances across the entire spring devices is superior to a positive control of the slats (see, e.g., EP 0215980 Al) that provides for exactly the same slat distances in that it is far less susceptible to damages that can arise from possible constraints. These constraints can be created due to construction (with very large bridging devices due to the limited possibility for an inclination of the cross- members) as well as due to external influences (e.g.: jamming of a slat due to dirt in the sliding surfaces, blocking of an individual gap due to dirt or foreign objects (e.g. rock) etc.). With narrow joint widths, the known bridging devices of the type specified above have indeed proven their worth. However, with average and in particular with large joint widths, special measures are required so as to prevent excessively large differences in the widths of the individual gap existing between, in each case, two mutually adjacent slats. The use of particularly low-friction sliding materials in the region of the support of the slats on the cross-members and/or the increase of the controlling forces via larger and harder control springs, respectively, deserve a particular mention here. These measures are associated with additional expenses and are not able to reliably prevent the particularly critical opening of individual gaps beyond a reliable measure with bridging devices that are designed for very large joint widths. With known bridging devices of the type specified above provided for particularly large joint widths, the latter requires the additional use of stops that confine the width of the individual gap. A mechanical coupling of mutually adjacent slats via activated stops, however, results in considerable dynamic stresses that, in turn, act to support wear. Incidentally, the stops are not suitable to contribute to a standardization of the gap widths of the individual gap below the maximally admissible gap width. - 3 - It is the object of the instant invention to provide a bridging -device of the type specified above that, with a comparatively low constructive and production effort, is particularly suitable for very large joint widths, in that especially the opening of individual gaps beyond an admissible measure is, as a rule, reliably avoided simply via the control springs, that is, without requiring stops for doing so. It would thereby be particularly desirable if the result thereof were a steadying effect for the gap widths of the individual gap in the remaining operating sectors of the bridging device, e.g., in the event of a comparatively small joint width. This object is solved with a bridging device of the type specified above in that the individual spring devices provide different controlling forces according to their arrangement inside the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction of the joint. The controlling forces of the individual spring devices that are different in the direction of the control chain allow, in particular, for a consideration of those frictional forces acting between the slats and the cross-members with a sliding support of the slats on the cross-members that have to be overcome in the event of a tracking of the slats due to a change of the joint width and that add up from slat to slat. In other words, according to the instant invention, the frictional forces that act between the slats and the cross-members and that restrain a compensatory movement of the slats in the event of a changing joint width and that add up in the case of cross-members being clamped on one side from one joint edge to the other joint edge and in the case of cross-members being supported on both sides so as to slide from both joint edges to the center of the joint are compensated by the controlling forces that change across the width of the joint. By - 4 - suitably tuning those controlling forces that are provided by the spring devices in the operating sector of large joint widths to the frictional forces that are different (summed up) in the direction of the control chain, an approximated balance of forces can be achieved between the controlling forces and the respective frictional forces that are to be overcome, whereby an inadmissibly large opening of individual gaps of the opening bridging device is prevented. Especially the opening of individual gaps beyond an admissible measure can be reliably avoided with the application of the instant invention for such generic bridging devices that are designed for particularly large joint widths and that accordingly have a particularly high number of slats (e.g., more than 15), generally solely with the specific tuning of the controlling force gradient according to the invention and thus without forced control of the slats and without the use of stops. However, the instant invention is not only advantageous in this regard. Instead, representing an absolutely surprising result, the invention can, under the conditions that will be described in more detail below, can also have a positive effect on a standardization of the slat distances in other operating states of the bridging device as well (e.g. with a comparatively small joint width). If one of the supports of the cross-members in the bridging device according to the invention is designed as a clamp and the other one is designed in a sliding manner, the gradient of the controlling force advantageously extends across the entire joint width. If, according to a preferred development of the invention, the spring devices, in the event of a maximal joint width, thereby each have a tension that acts in terms of a decrease of the slat distance, the controlling force gradient must be chosen in such a manner that the respective controlling force of the spring devices - 5 - increases in the direction from the clamp of the cross- members towards their sliding support. In case of a reversed tension that acts in terms of an increase of the slat distance in the event of a maximal joint width, the gradient extends in opposite direction. The above applies independent on whether the spring devices, according to a further preferred development of the invention, are substantially tension-free in a nominal position that lies between the maximally and the minimally admissible joint width or whether the spring devices, across the entire operating range of the bridging device, have a tension that acts in the same direction in terms of a decrease or an increase of the slat distance. The same applies in the case of a two-sided sliding support of the cross-members, that is, on the abutment as well as on the superstructure, provided that two opposite controlling force gradients prevail on both sides of a more or less centrally placed slat. Particularly in this case, provided that the spring devices have a tension in terms of a decrease of the slat distance in the event of a maximal joint width, the respective controlling force of the spring devices can increase in the direction from the center of the joint to the edges of the joint. This development will be discussed in detail below. Particular advantages of the invention arise if the spring devices in terms of the above explanations are substantially tension-free in a nominal position that lies between the maximally and the minimally admissible joint width and if the spring devices that provide different controlling forces have different degrees of stiffness, that is, differently steep force-displacement characteristics. This is so because, in this case, the controlling force gradient has a standardizing effect on the slat distances when opening the joint in the region of large joint widths as well as when closing the joint in the - 6 - region of small joint widths. In so doing, a mechanical contact of the slats is effectively ruled out in operating positions that are close to the minimal joint width as well. In bridging devices, where the spring devices, in abandonment of the above-presented additional advantages, are not substantially tension-free in a nominal position located between the maximally and the minimally admissible joint width but instead are tensioned across the entire operating sector of the bridging device, it is also possible in the context of the instant invention that the spring units that provide different controlling forces do not have different degrees of stiffness, but are instead highly pretensioned to different degrees according to the controlling force gradient. The above-explained advantages that can be achieved if the instant invention is applied, are particularly pronounced, if the cross-members are supported so as to slide on both sides, that is, on the abutment as well as on the superstructure. This is so because, in this case, the respective frictional forces that sum up and that are to be compensated via the controlling force gradients according to the invention are cut in half. The result is a particularly slight deviation of the slats from their target position. In application of the above-explained basic principles and in accordance with the invention, the individual spring devices provide different controlling forces in such a bridging device comprising cross-members that are supported so as to slide on both sides, whereby the respective controlling force of the spring devices increases or decreases via two opposite controlling force gradients, in each case from the center of the joint gap in the direction of its edges - according to the direction of the tension of the spring units. If the spring devices, at maximal joint width, have a tension that acts in terms of a - 7 - decrease of the slat distance, the respective controlling force of the spring devices increases in the direction from the center of the cross-members to the edges of the joint. In the event of a tension of the spring devices at maximal joint width in terms of an increase of the slat distance, the respective controlling force of the spring devices, in contrast, decreases in the direction from the center of the cross-members to the edges of the joint. If all of the slats or, if applicable, all of the slats except for one that is centrally placed, are supported on the cross-members so as to slide, said cross-members can, in the event of a two-sided sliding positioning of the cross-members, be positively controlled according to yet another preferred development of the invention in such a manner that the center of the cross-members, relating to the joint center, is constant independent on the current joint width. Rope controls, for example, are possible here, such as they are known from the positive control of slats. Such a positive control of the cross-members is also advantageous and especially if all of the slats are supported so as to slide on the cross-members, that is, if a middle slat is also not rigidly connected with the cross- members. Meanwhile, it will be possible to do without such a positive control of the cross-members in most practically relevant applications. Obviously, the instant invention is incidentally also suited for application in such bridging devices, in which the slats and a number of slats, respectively, in each case comprising different cross- members that are supported on both sides so as to slide, are rigidly connected and in which the cross-members thus shift to a varying degree in the event of a changing joint width. This is so because the frictional forces between the cross-members and the superstructure and the abutment, respectively, that add up in the direction of the control chain, can also be compensated here with the use of the invention in terms of a balance of forces. - 8 - With bridging devices that are designed for extremely large joint widths (e.g. with 30 or more slats), it may be advantageous if a part of the slats, for example a portion between 5% and 15%, is positively controlled in an intermittent arrangement or is additionally controlled via another system by means of a spring. Especially every tenth slat can thus be positively controlled. In turn, the measures inherently known for the positive control of slats, such as rope controls, for example, lend themselves for this purpose. It was already presented above that the provision of different controlling forces by the individual spring devices can be realized under certain conditions by means of a differently high pretension of the respective spring units or that the spring devices can have different degrees of stiffness in that they comprise different spring units comprising differently steep force-displacement characteristics. Additional possibilities for providing spring devices comprising different degrees of stiffness lie in that the spring devices comprise different amounts of identical spring units or different spring units, the spring elements of which (e.g. elastomer blocks) have different force-displacement characteristics (e.g. by different measurements or different material selection). If necessary, the illustrated measures can also be (randomly) combined with one another. The maximal total incline of the controlling force effected by the controlling force gradient depends on a series of impact variables, such as, in particular, the style of the bridging device (cross-members supported so as to slide on one side or on both sides), the amount of slats and the sliding behavior of the slats on the cross-members. The total incline thus generally increases with the number of - 9 - the slats and with the increase of the frictional value of the sliding support of the slats. The instant invention can be converted with spring devices of the most diverse designs. Particularly good results can thereby be achieved by means of spring devices that comprise spring elements designed as elastomer springs, whereby the corresponding elastomer blocks are stressed in particular on impulse. In this respect, a development of the invention that is particularly preferable in terms of overall size and costs is characterized in that the spring units of two adjacent spring devices are coupled in each case via a plate that is rigidly connected with the middle one.of three adjacent slats with both adjacent slats, being connected to the plate via thrust springs in the form of elastomer blocks. Preferably, the elastomer blocks are tension-free in a neutral position of the bridging device that lies between the minimal and the maximal gap width (see above). According to a further aspect of the instant invention, the spring devices can comprise spring units that are placed in each case between two adjacent cross-members so as to be distributed on a number of control bays that are placed in each case between two mutually adjacent cross-members, whereby abrupt increases of the controlling force within the control chain of the individual control bays are offset to one another in the different control bays. With the use of identical spring elements, which is advantageous in consideration of costs, this also allows, in the context of the entire device, for a smoothing of the controlling force increases existing within the individual control bays with the result of a virtually or completely uniform gradient of the controlling force of the entire device. For clarification purposes, it is pointed out that in the context of the instant invention, the controlling force - 10 - according to the relevant gradient must not necessarily increase and decrease, respectively, from individual gap to individual gap. Instead, it is also possible that a number of mutually adjacent slats form a group in the sense that the spring devices acting between them are designed for corresponding controlling forces. The deviations from a theoretically optimal controlling force characteristic that is connected therewith is justifiable and is warrantable by cost savings. Likewise, only for the purpose of clarification, it is pointed out that with bridging devices according to the invention, additional stop-like devices could also be provided, possibly as supplemental safety measures, which, in case of a disruption of the normal function prevent the local opening of individual gaps beyond the admissible measure. Such devices, however, do not have any effect in normal operation, because, due to the design of the control chain that is characteristic for the invention, the at least largely even distance of the slats and, in particular, the adherence to individual gap widths within the admissible range is ensured solely by means of the control springs. The instant invention will be explained in more detail below by means of a preferred exemplary embodiment illustrated in the drawing. Fig. 1 shows a vertical section guided in the region of a cross-member transversal to the longitudinal direction of the joint through a bridging device according to the invention, Fig. 2 shows in a view from below the region of the bridging device according to Fig. 1 located between two cross-members and - 11 - Fig. 3 shows a vertical section through the bridging device according to Figs. 1 and 2 along the line III-III. The bridging device 1 for an expansion joint 4 placed between an abutment 2 and a superstructure 3 reproduced in the drawing comprises a number of cross-members 5 that- bridging the joint gap - extend between the superstructure 3 and the abutment 2 and that are supported on the abutment and on the superstructure. The cross-members 5 are thereby clamped on the superstructure 3. Meanwhile, provision is made on the abutment 2 for a sliding support 6 of the cross-members, said sliding support 6 allowing for a relative movement (double arrow A) of the cross-members 5 in its longitudinal direction, relating to the abutment 2. A multitude of slats 7 extending in a longitudinal direction of the joint (double arrow B) are placed between the abutment 2 and the superstructure 3 and are supported so as to slide on the cross-members 5. In view of a bearing that is safe from being lifted off and in view of a canting-free position of the slats, each slat is installed on fasteners 8 that encompass the cross-members 5 and on which sliding sliding blocks 9, 10 are attached on assigned sliding surfaces of the cross-members. Those of the sliding blocks 9, 10 that are placed below the cross-members also serve for pretensioning the units. The distance of two mutually adjacent slats 7 to one another is also controlled by means of spring devices 11 to which the respective slats are connected. The totality of all spring devices 11 forms a control chain that extends from the abutment 2 to the superstructure 3. To the extent set forth above, the bridging device according the drawing corresponds to the inherently known state of the art so that, in this respect, detailed explanations are not necessary. - 12 - Each spring device 11 comprises a multitude of spring units 12 that are distributed in longitudinal direction of the joint B and that are each placed between the cross-members 5. Viewed from the superstructure 3, the two spring units 1212-13.1 and 1212-13.2 are effective between the 12th slat -712 and the 13th slat 713 between the two cross-members 51 and 52. Further spring units of the corresponding spring device 1112-13 are placed between further cross-members. The spring unit 1212-13.1 comprises a plate 13 that is rigidly connected with the slat 713 via a bar 14 and a spring element 1512-13 in the form of an elastomer spring 1612-13. Said elastomer spring is stressed on impulse, for the purpose of which it is connected with the plate 13 from below and is fixed to the lower side of the slat 712 at the top. The spring unit 1212-13.2 comprises a plate 17 that is accordingly fixedly connected with the slat 712 via a bar and two spring elements in the form of two elastomer springs that are stressed on impulse. Viewed over the entire length of the slats, the spring units are placed as symmetrically as possible so as to obtain a distribution of the controlling forces acting between the respective slats that is free from moments about the vertical axis. In view of a design of the entire spring system that is as compact as possible, each of said plates is assigned to two mutually adjacent spring units. The plate 13 is thus extended beyond the slat 713 as far as below the slat 714. The elastomer spring I613-14 that forms the spring element 1513-14 that is connected to the lower side of the slat 714 is also connected therewith. Substantially the same holds true for the connection of the control chain to the abutment 2 and to the superstructure 3 as for the connection of two slats among one another. The spring device llÜ-1 acting between the superstructure 3 and the adjacent slat 71 comprises in each case a spring unit - 13 - 12Ü-1 between two mutually adjacent cross-members. Said spring unit 12Ü-1 comprises a plate 18 that is rigidly connected with the slat 71 via a bar 19 and two spring elements 15Ü-1 in the form of two elastomer springs I6Ü-1 stressed on impulse. Said elastomer springs I6Ü-1 are fixed on top on the lower side of a counterplate 20 that is fixedly connected with the superstructure 3 via a console 21. In the case of the spring device 1126-W acting between the 2 6th slat 726 and the abutment 2, the spring unit 1226-w comprises four elastomer springs that are stressed on impulse. As is particularly illustrated in Fig. 3, the individual spring devices 11 provide different controlling forces according to their arrangement inside the device. That is to say, the increase of the number of spring elements 15 provided per spring unit 12 from the superstructure 3 in the direction of the abutment 2, the stiffness of the spring units 12 increases from the superstructure 3 in the direction of the abutment 2 so that, as a result, the respective controlling force of the spring devices 12 has,a gradient transversal to the longitudinal direction of the joint. Within the control bay illustrated in Fig. 3, the controlling force increase from the superstructure 3 in the direction of the abutment 2 in two jumps, that is, at the 11th slat 711 and at the 20th slat 720. For the standardization of the controlling force gradient within the entire device, that is, including the individual control chains that are placed so as to be distributed across all of the control bays, the controlling force jumps in the other control bays are offset to those of the control bay illustrated in Fig. 3. The figure shows the bridging device in a nominal position that lies between the maximally and the minimally admissible joint width. Fig. 3 illustrates graphically that the spring units 12 in this nominal position are - 14 - substantially tension-free so that, in the event of a joint width assigned to that above the nominal position, the spring devices 11 have a tension in terms of a decrease of the slat distance and in the event of a joint width assigned to that below the nominal position, the spring devices 11 have a tension in terms of an increase of the slat distance. WO 2006/074892 Al CLAIMS 1. A bridging device for an expansion joint (4) in a structure fit for traffic, said expansion joint (4) being placed between an abutment (2) and a superstructure (3) comprising the following features: - a number of cross-members (5) that bridge the joint gap extend between the abutment and the superstructure and are supported on the abutment and on the superstructure; - a multitude of slats (7) extending in a longitudinal direction of the joint are placed between the abutment and the superstructure and are each supported on at least one portion of the cross-members; - the distance of the slats from one another is controlled by spring devices (11) to which the relevant slats are connected; characterized in that the individual spring devices provide different controlling forces according to their arrangement inside the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction (B) of the joint. 2. The bridging device according to claim 1, characterized in that in each case one of the supports of the cross- members (5) is designed as a clamp and the other one is designed so as to slide, whereby the gradient of the controlling force extends across the entire width of the joint. 3. The bridging device according to claim 2, characterized in -16 - that, with a maximum joint width, the spring devices (11) have a tension in terms of a decrease of the slat distance and the respective controlling force of the spring devices increases in the direction of the clamping of the cross-members (5) to their sliding support (6). 4. The bridging device according to claim 1, characterized in that the cross-members (5) are supported so as to slide on the abutment (2) and on the superstructure (3) . 5. The bridging device according to claim 4, characterized in that two opposite controlling force gradients are provided on both sides of the center of the cross- members . 6. The bridging device according to claim 5, characterized in that, with maximum joint width, the spring devices have a tension in terms of a decrease of the slat distance and the respective controlling force of the spring devices increases in the direction from the center of the cross-members to the edges of the joint. 7. The bridging device according to one of claims 4 to 6, characterized in that the cross-members (5) are positively controlled in such a manner that their center, relating to the joint center, is constant independent on the current joint width. 8. The bridging device according to one of claims 1 to 7, characterized in that the spring devices (11) are substantially tension-free in a nominal position located between the maximally and the minimally admissible joint width. 9. The bridging device according to one of claims 1 to 8, characterized in that all of the slats (7) are supported so as to slide on the cross-members (5) . 10. The bridging device according to one of claims 1 to 9, characterized in that a part of the slats (7) is positively controlled in an intermittent arrangement or is additionally controlled via another system by means of a spring. 11. The bridging device according to claim 10, characterized in that the portion of the controlled slats is between 5% and 15%. 12. The bridging device according to claim 4, characterized in that maximally one slat that is substantially placed centrally is fixedly connected with the cross- members. 13. The bridging device according to claim 4, 9 characterized in that a number of slats are fixedly connected with respectively different cross-members. 14. The bridging device according to one of claims 1 to 13, characterized in that the spring devices (11) that provide different controlling forces have different degrees of stiffness. 15. The bridging device according to claim 14, characterized in that the spring devices (11) that have different degrees of stiffness have a different number of identical spring units. 16. The bridging device according to claim 14, characterized in that the spring devices (11) that have different degrees of stiffness comprise different spring units (12) with differently steep force-displacement characteristics. 17. The bridging device according to claim 16, characterized in that the spring units that have differently steep force-displacement characteristics have a different number of identical spring elements. 18. The bridging device according to one of claims 1 to 13, characterized in that the spring devices (11) that provide different controlling forces have spring units (12) that are pretensioned to different degrees. 19. The bridging device according to one of claims 1 to 18, characterized in 19 that, with a maximum joint width, the controlling force of the spring device comprising the maximum controlling force is at least 1.7-fold the controlling force of the spring device comprising the minimal controlling force. 20. The bridging device according to one of claims 1 to 19, characterized in that the spring devices (11) comprise spring elements (15) that are designed as elastomer springs (16). 21. The bridging device according to one of claims 1 to 20, characterized in that the spring units (12) of two adjacent spring devices (11) are structurally coupled. 22. The bridging device according to claim 21, characterized in that the spring units (12) of two adjacent spring devices (11) are coupled in each case via a plate (13, 17) that is rigidly connected with the middle one of three adjacent slats (7) with both adjacent slats being connected to the plate (13, 17) via spring elements (15). 23. The bridging device according to one of claims 1 to 22, characterized in that the spring devices (11) comprise spring units (12) that, in each case, are placed on a number of control bays that are placed in each case between two adjacent cross-members (5), whereby abrupt increases in the controlling force within the control chain of the individual control bays are offset to one another in the different control bays. The invention relates to a bridging device for an expansion joint (4) in a structure fit for traffic, said expansion joint being placed between an abutment (2) and a superstructure (3). A number of cross-members (5) that bridge the joint gap extend between the abutment and the superstructure and are supported on the abutment and on the superstructure. A multitude of slats (7) extending in a longitudinal direction of the gap are placed between the abutment and superstructure and are each supported on at least one portion of the cross-members. The distance of the slats from one another is controlled by spring devices to which the relevant slats are connected. The individual spring devices provide different controlling forces according to their arrangement inside the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction of the joint.

Full Text

WO 2006/074892 Al
BRIDGING DEVICE FOR AN EXPANSION JOINT IN A STRUCTURE FIT
FOR TRAFFIC
The instant invention relates to a bridging device for an
expansion joint fit for traffic, said expansion joint being
placed between an abutment and a superstructure comprising
the following features:
a number of cross-members that bridge the joint gap
extend between the abutment and the superstructure and
are supported on the abutment and on the
superstructure;
a multitude of slats extending in a longitudinal
direction of the joint are placed between the abutment
and the superstructure and are each supported on at
least one portion of the cross-members;
the distance of the slats from one another is
controlled by spring devices to which the relevant
slats are connected.
Bridging devices of the type specified above, as they are
used in particular in bridge building, are known in
different designs. Possibilities for variations thereby
exist, for example, with regard to the positioning of the
cross-members in that one side thereof can be fixedly
clamped (see, e.g., DE 19607593 Al) or in that they can be
supported so as to slide on the abutment as well as on the
superstructure (see, e.g., DE 3201751 C2). The slats can be
supported so as to slide on all of the cross-members or
individual slats or all of the slats are fixedly connected
with assigned cross-members that, in each case, are
supported so as to slide on the superstructure as well as
on the abutment, whereby, in this case, a sliding support
of the slats on the remaining cross-members is possible,
but not imperative. The spring devices that are connected
in serj.es in the form of a control chain are thereby
supposed to provide for the most even distances of the

- 2 -
slats to one another. Such a control of the slat distances
across the entire spring devices is superior to a positive
control of the slats (see, e.g., EP 0215980 Al) that
provides for exactly the same slat distances in that it is
far less susceptible to damages that can arise from
possible constraints. These constraints can be created due
to construction (with very large bridging devices due to
the limited possibility for an inclination of the cross-
members) as well as due to external influences (e.g.:
jamming of a slat due to dirt in the sliding surfaces,
blocking of an individual gap due to dirt or foreign
objects (e.g. rock) etc.).
With narrow joint widths, the known bridging devices of the
type specified above have indeed proven their worth.
However, with average and in particular with large joint
widths, special measures are required so as to prevent
excessively large differences in the widths of the
individual gap existing between, in each case, two mutually
adjacent slats. The use of particularly low-friction
sliding materials in the region of the support of the slats
on the cross-members and/or the increase of the controlling
forces via larger and harder control springs, respectively,
deserve a particular mention here. These measures are
associated with additional expenses and are not able to
reliably prevent the particularly critical opening of
individual gaps beyond a reliable measure with bridging
devices that are designed for very large joint widths. With
known bridging devices of the type specified above provided
for particularly large joint widths, the latter requires
the additional use of stops that confine the width of the
individual gap. A mechanical coupling of mutually adjacent
slats via activated stops, however, results in considerable
dynamic stresses that, in turn, act to support wear.
Incidentally, the stops are not suitable to contribute to a
standardization of the gap widths of the individual gap
below the maximally admissible gap width.

- 3 -
It is the object of the instant invention to provide a
bridging -device of the type specified above that, with a
comparatively low constructive and production effort, is
particularly suitable for very large joint widths, in that
especially the opening of individual gaps beyond an
admissible measure is, as a rule, reliably avoided simply
via the control springs, that is, without requiring stops
for doing so. It would thereby be particularly desirable if
the result thereof were a steadying effect for the gap
widths of the individual gap in the remaining operating
sectors of the bridging device, e.g., in the event of a
comparatively small joint width.
This object is solved with a bridging device of the type
specified above in that the individual spring devices
provide different controlling forces according to their
arrangement inside the device, whereby the respective
controlling force of the spring devices has a gradient
transversal to the longitudinal direction of the joint. The
controlling forces of the individual spring devices that
are different in the direction of the control chain allow,
in particular, for a consideration of those frictional
forces acting between the slats and the cross-members with
a sliding support of the slats on the cross-members that
have to be overcome in the event of a tracking of the slats
due to a change of the joint width and that add up from
slat to slat. In other words, according to the instant
invention, the frictional forces that act between the slats
and the cross-members and that restrain a compensatory
movement of the slats in the event of a changing joint
width and that add up in the case of cross-members being
clamped on one side from one joint edge to the other joint
edge and in the case of cross-members being supported on
both sides so as to slide from both joint edges to the
center of the joint are compensated by the controlling
forces that change across the width of the joint. By

- 4 -
suitably tuning those controlling forces that are provided
by the spring devices in the operating sector of large
joint widths to the frictional forces that are different
(summed up) in the direction of the control chain, an
approximated balance of forces can be achieved between the
controlling forces and the respective frictional forces
that are to be overcome, whereby an inadmissibly large
opening of individual gaps of the opening bridging device
is prevented.
Especially the opening of individual gaps beyond an
admissible measure can be reliably avoided with the
application of the instant invention for such generic
bridging devices that are designed for particularly large
joint widths and that accordingly have a particularly high
number of slats (e.g., more than 15), generally solely with
the specific tuning of the controlling force gradient
according to the invention and thus without forced control
of the slats and without the use of stops. However, the
instant invention is not only advantageous in this regard.
Instead, representing an absolutely surprising result, the
invention can, under the conditions that will be described
in more detail below, can also have a positive effect on a
standardization of the slat distances in other operating
states of the bridging device as well (e.g. with a
comparatively small joint width).
If one of the supports of the cross-members in the bridging
device according to the invention is designed as a clamp
and the other one is designed in a sliding manner, the
gradient of the controlling force advantageously extends
across the entire joint width. If, according to a preferred
development of the invention, the spring devices, in the
event of a maximal joint width, thereby each have a tension
that acts in terms of a decrease of the slat distance, the
controlling force gradient must be chosen in such a manner
that the respective controlling force of the spring devices

- 5 -
increases in the direction from the clamp of the cross-
members towards their sliding support. In case of a
reversed tension that acts in terms of an increase of the
slat distance in the event of a maximal joint width, the
gradient extends in opposite direction. The above applies
independent on whether the spring devices, according to a
further preferred development of the invention, are
substantially tension-free in a nominal position that lies
between the maximally and the minimally admissible joint
width or whether the spring devices, across the entire
operating range of the bridging device, have a tension that
acts in the same direction in terms of a decrease or an
increase of the slat distance.
The same applies in the case of a two-sided sliding support
of the cross-members, that is, on the abutment as well as
on the superstructure, provided that two opposite
controlling force gradients prevail on both sides of a more
or less centrally placed slat. Particularly in this case,
provided that the spring devices have a tension in terms of
a decrease of the slat distance in the event of a maximal
joint width, the respective controlling force of the spring
devices can increase in the direction from the center of
the joint to the edges of the joint. This development will
be discussed in detail below.
Particular advantages of the invention arise if the spring
devices in terms of the above explanations are
substantially tension-free in a nominal position that lies
between the maximally and the minimally admissible joint
width and if the spring devices that provide different
controlling forces have different degrees of stiffness,
that is, differently steep force-displacement
characteristics. This is so because, in this case, the
controlling force gradient has a standardizing effect on
the slat distances when opening the joint in the region of
large joint widths as well as when closing the joint in the

- 6 -
region of small joint widths. In so doing, a mechanical
contact of the slats is effectively ruled out in operating
positions that are close to the minimal joint width as
well.
In bridging devices, where the spring devices, in
abandonment of the above-presented additional advantages,
are not substantially tension-free in a nominal position
located between the maximally and the minimally admissible
joint width but instead are tensioned across the entire
operating sector of the bridging device, it is also
possible in the context of the instant invention that the
spring units that provide different controlling forces do
not have different degrees of stiffness, but are instead
highly pretensioned to different degrees according to the
controlling force gradient.
The above-explained advantages that can be achieved if the
instant invention is applied, are particularly pronounced,
if the cross-members are supported so as to slide on both
sides, that is, on the abutment as well as on the
superstructure. This is so because, in this case, the
respective frictional forces that sum up and that are to be
compensated via the controlling force gradients according
to the invention are cut in half. The result is a
particularly slight deviation of the slats from their
target position. In application of the above-explained
basic principles and in accordance with the invention, the
individual spring devices provide different controlling
forces in such a bridging device comprising cross-members
that are supported so as to slide on both sides, whereby
the respective controlling force of the spring devices
increases or decreases via two opposite controlling force
gradients, in each case from the center of the joint gap in
the direction of its edges - according to the direction of
the tension of the spring units. If the spring devices, at
maximal joint width, have a tension that acts in terms of a

- 7 -
decrease of the slat distance, the respective controlling
force of the spring devices increases in the direction from
the center of the cross-members to the edges of the joint.
In the event of a tension of the spring devices at maximal
joint width in terms of an increase of the slat distance,
the respective controlling force of the spring devices, in
contrast, decreases in the direction from the center of the
cross-members to the edges of the joint.
If all of the slats or, if applicable, all of the slats
except for one that is centrally placed, are supported on
the cross-members so as to slide, said cross-members can,
in the event of a two-sided sliding positioning of the
cross-members, be positively controlled according to yet
another preferred development of the invention in such a
manner that the center of the cross-members, relating to
the joint center, is constant independent on the current
joint width. Rope controls, for example, are possible here,
such as they are known from the positive control of slats.
Such a positive control of the cross-members is also
advantageous and especially if all of the slats are
supported so as to slide on the cross-members, that is, if
a middle slat is also not rigidly connected with the cross-
members. Meanwhile, it will be possible to do without such
a positive control of the cross-members in most practically
relevant applications. Obviously, the instant invention is
incidentally also suited for application in such bridging
devices, in which the slats and a number of slats,
respectively, in each case comprising different cross-
members that are supported on both sides so as to slide,
are rigidly connected and in which the cross-members thus
shift to a varying degree in the event of a changing joint
width. This is so because the frictional forces between the
cross-members and the superstructure and the abutment,
respectively, that add up in the direction of the control
chain, can also be compensated here with the use of the
invention in terms of a balance of forces.

- 8 -
With bridging devices that are designed for extremely large
joint widths (e.g. with 30 or more slats), it may be
advantageous if a part of the slats, for example a portion
between 5% and 15%, is positively controlled in an
intermittent arrangement or is additionally controlled via
another system by means of a spring. Especially every tenth
slat can thus be positively controlled. In turn, the
measures inherently known for the positive control of
slats, such as rope controls, for example, lend themselves
for this purpose.
It was already presented above that the provision of
different controlling forces by the individual spring
devices can be realized under certain conditions by means
of a differently high pretension of the respective spring
units or that the spring devices can have different degrees
of stiffness in that they comprise different spring units
comprising differently steep force-displacement
characteristics. Additional possibilities for providing
spring devices comprising different degrees of stiffness
lie in that the spring devices comprise different amounts
of identical spring units or different spring units, the
spring elements of which (e.g. elastomer blocks) have
different force-displacement characteristics (e.g. by
different measurements or different material selection). If
necessary, the illustrated measures can also be (randomly)
combined with one another.
The maximal total incline of the controlling force effected
by the controlling force gradient depends on a series of
impact variables, such as, in particular, the style of the
bridging device (cross-members supported so as to slide on
one side or on both sides), the amount of slats and the
sliding behavior of the slats on the cross-members. The
total incline thus generally increases with the number of

- 9 -
the slats and with the increase of the frictional value of
the sliding support of the slats.
The instant invention can be converted with spring devices
of the most diverse designs. Particularly good results can
thereby be achieved by means of spring devices that
comprise spring elements designed as elastomer springs,
whereby the corresponding elastomer blocks are stressed in
particular on impulse. In this respect, a development of
the invention that is particularly preferable in terms of
overall size and costs is characterized in that the spring
units of two adjacent spring devices are coupled in each
case via a plate that is rigidly connected with the middle
one.of three adjacent slats with both adjacent slats, being
connected to the plate via thrust springs in the form of
elastomer blocks. Preferably, the elastomer blocks are
tension-free in a neutral position of the bridging device
that lies between the minimal and the maximal gap width
(see above).
According to a further aspect of the instant invention, the
spring devices can comprise spring units that are placed in
each case between two adjacent cross-members so as to be
distributed on a number of control bays that are placed in
each case between two mutually adjacent cross-members,
whereby abrupt increases of the controlling force within
the control chain of the individual control bays are offset
to one another in the different control bays. With the use
of identical spring elements, which is advantageous in
consideration of costs, this also allows, in the context of
the entire device, for a smoothing of the controlling force
increases existing within the individual control bays with
the result of a virtually or completely uniform gradient of
the controlling force of the entire device.
For clarification purposes, it is pointed out that in the
context of the instant invention, the controlling force

- 10 -
according to the relevant gradient must not necessarily
increase and decrease, respectively, from individual gap to
individual gap. Instead, it is also possible that a number
of mutually adjacent slats form a group in the sense that
the spring devices acting between them are designed for
corresponding controlling forces. The deviations from a
theoretically optimal controlling force characteristic that
is connected therewith is justifiable and is warrantable by
cost savings.
Likewise, only for the purpose of clarification, it is
pointed out that with bridging devices according to the
invention, additional stop-like devices could also be
provided, possibly as supplemental safety measures, which,
in case of a disruption of the normal function prevent the
local opening of individual gaps beyond the admissible
measure. Such devices, however, do not have any effect in
normal operation, because, due to the design of the control
chain that is characteristic for the invention, the at
least largely even distance of the slats and, in
particular, the adherence to individual gap widths within
the admissible range is ensured solely by means of the
control springs.
The instant invention will be explained in more detail
below by means of a preferred exemplary embodiment
illustrated in the drawing.
Fig. 1 shows a vertical section guided in the region of a
cross-member transversal to the longitudinal
direction of the joint through a bridging device
according to the invention,
Fig. 2 shows in a view from below the region of the
bridging device according to Fig. 1 located between
two cross-members and

- 11 -
Fig. 3 shows a vertical section through the bridging device
according to Figs. 1 and 2 along the line III-III.
The bridging device 1 for an expansion joint 4 placed
between an abutment 2 and a superstructure 3 reproduced in
the drawing comprises a number of cross-members 5 that-
bridging the joint gap - extend between the superstructure
3 and the abutment 2 and that are supported on the abutment
and on the superstructure. The cross-members 5 are thereby
clamped on the superstructure 3. Meanwhile, provision is
made on the abutment 2 for a sliding support 6 of the
cross-members, said sliding support 6 allowing for a
relative movement (double arrow A) of the cross-members 5
in its longitudinal direction, relating to the abutment 2.
A multitude of slats 7 extending in a longitudinal
direction of the joint (double arrow B) are placed between
the abutment 2 and the superstructure 3 and are supported
so as to slide on the cross-members 5. In view of a bearing
that is safe from being lifted off and in view of a
canting-free position of the slats, each slat is installed
on fasteners 8 that encompass the cross-members 5 and on
which sliding sliding blocks 9, 10 are attached on assigned
sliding surfaces of the cross-members. Those of the sliding
blocks 9, 10 that are placed below the cross-members also
serve for pretensioning the units. The distance of two
mutually adjacent slats 7 to one another is also controlled
by means of spring devices 11 to which the respective slats
are connected. The totality of all spring devices 11 forms
a control chain that extends from the abutment 2 to the
superstructure 3.
To the extent set forth above, the bridging device
according the drawing corresponds to the inherently known
state of the art so that, in this respect, detailed
explanations are not necessary.

- 12 -
Each spring device 11 comprises a multitude of spring units
12 that are distributed in longitudinal direction of the
joint B and that are each placed between the cross-members
5. Viewed from the superstructure 3, the two spring units
1212-13.1 and 1212-13.2 are effective between the 12th slat -712
and the 13th slat 713 between the two cross-members 51 and
52. Further spring units of the corresponding spring device
1112-13 are placed between further cross-members.
The spring unit 1212-13.1 comprises a plate 13 that is
rigidly connected with the slat 713 via a bar 14 and a
spring element 1512-13 in the form of an elastomer spring
1612-13. Said elastomer spring is stressed on impulse, for
the purpose of which it is connected with the plate 13 from
below and is fixed to the lower side of the slat 712 at the
top. The spring unit 1212-13.2 comprises a plate 17 that is
accordingly fixedly connected with the slat 712 via a bar
and two spring elements in the form of two elastomer
springs that are stressed on impulse. Viewed over the
entire length of the slats, the spring units are placed as
symmetrically as possible so as to obtain a distribution of
the controlling forces acting between the respective slats
that is free from moments about the vertical axis.
In view of a design of the entire spring system that is as
compact as possible, each of said plates is assigned to two
mutually adjacent spring units. The plate 13 is thus
extended beyond the slat 713 as far as below the slat 714.
The elastomer spring I613-14 that forms the spring element
1513-14 that is connected to the lower side of the slat 714
is also connected therewith.
Substantially the same holds true for the connection of the
control chain to the abutment 2 and to the superstructure 3
as for the connection of two slats among one another. The
spring device llÜ-1 acting between the superstructure 3 and
the adjacent slat 71 comprises in each case a spring unit

- 13 -
12Ü-1 between two mutually adjacent cross-members. Said
spring unit 12Ü-1 comprises a plate 18 that is rigidly
connected with the slat 71 via a bar 19 and two spring
elements 15Ü-1 in the form of two elastomer springs I6Ü-1
stressed on impulse. Said elastomer springs I6Ü-1 are fixed
on top on the lower side of a counterplate 20 that is
fixedly connected with the superstructure 3 via a console
21. In the case of the spring device 1126-W acting between
the 2 6th slat 726 and the abutment 2, the spring unit 1226-w
comprises four elastomer springs that are stressed on
impulse.
As is particularly illustrated in Fig. 3, the individual
spring devices 11 provide different controlling forces
according to their arrangement inside the device. That is
to say, the increase of the number of spring elements 15
provided per spring unit 12 from the superstructure 3 in
the direction of the abutment 2, the stiffness of the
spring units 12 increases from the superstructure 3 in the
direction of the abutment 2 so that, as a result, the
respective controlling force of the spring devices 12 has,a
gradient transversal to the longitudinal direction of the
joint. Within the control bay illustrated in Fig. 3, the
controlling force increase from the superstructure 3 in the
direction of the abutment 2 in two jumps, that is, at the
11th slat 711 and at the 20th slat 720. For the
standardization of the controlling force gradient within
the entire device, that is, including the individual
control chains that are placed so as to be distributed
across all of the control bays, the controlling force jumps
in the other control bays are offset to those of the
control bay illustrated in Fig. 3.
The figure shows the bridging device in a nominal position
that lies between the maximally and the minimally
admissible joint width. Fig. 3 illustrates graphically that
the spring units 12 in this nominal position are

- 14 -
substantially tension-free so that, in the event of a joint
width assigned to that above the nominal position, the
spring devices 11 have a tension in terms of a decrease of
the slat distance and in the event of a joint width
assigned to that below the nominal position, the spring
devices 11 have a tension in terms of an increase of the
slat distance.

WO 2006/074892 Al
CLAIMS
1. A bridging device for an expansion joint (4) in a
structure fit for traffic, said expansion joint (4)
being placed between an abutment (2) and a
superstructure (3) comprising the following
features:
- a number of cross-members (5) that bridge the
joint gap extend between the abutment and the
superstructure and are supported on the abutment
and on the superstructure;
- a multitude of slats (7) extending in a
longitudinal direction of the joint are placed
between the abutment and the superstructure and
are each supported on at least one portion of the
cross-members;
- the distance of the slats from one another is
controlled by spring devices (11) to which the
relevant slats are connected;
characterized in
that the individual spring devices provide different
controlling forces according to their arrangement
inside the device, whereby the respective
controlling force of the spring devices has a
gradient transversal to the longitudinal direction
(B) of the joint.
2. The bridging device according to claim 1,
characterized in
that in each case one of the supports of the cross-
members (5) is designed as a clamp and the other one
is designed so as to slide, whereby the gradient of
the controlling force extends across the entire
width of the joint.
3. The bridging device according to claim 2,
characterized in

-16 -
that, with a maximum joint width, the spring devices
(11) have a tension in terms of a decrease of the
slat distance and the respective controlling force
of the spring devices increases in the direction of
the clamping of the cross-members (5) to their
sliding support (6).
4. The bridging device according to claim 1,
characterized in
that the cross-members (5) are supported so as to
slide on the abutment (2) and on the superstructure
(3) .
5. The bridging device according to claim 4,
characterized in
that two opposite controlling force gradients are
provided on both sides of the center of the cross-
members .
6. The bridging device according to claim 5,
characterized in
that, with maximum joint width, the spring devices
have a tension in terms of a decrease of the slat
distance and the respective controlling force of the
spring devices increases in the direction from the
center of the cross-members to the edges of the
joint.
7. The bridging device according to one of claims 4 to
6,
characterized in
that the cross-members (5) are positively controlled
in such a manner that their center, relating to the
joint center, is constant independent on the current
joint width.

8. The bridging device according to one of claims 1 to
7,
characterized in
that the spring devices (11) are substantially
tension-free in a nominal position located between
the maximally and the minimally admissible joint
width.
9. The bridging device according to one of claims 1 to
8,
characterized in
that all of the slats (7) are supported so as to
slide on the cross-members (5) .
10. The bridging device according to one of claims 1 to
9,
characterized in
that a part of the slats (7) is positively
controlled in an intermittent arrangement or is
additionally controlled via another system by means
of a spring.
11. The bridging device according to claim 10,
characterized in
that the portion of the controlled slats is between
5% and 15%.
12. The bridging device according to claim 4,
characterized in
that maximally one slat that is substantially placed
centrally is fixedly connected with the cross-
members.
13. The bridging device according to claim 4,
9 characterized in
that a number of slats are fixedly connected with
respectively different cross-members.

14. The bridging device according to one of claims 1 to
13,
characterized in
that the spring devices (11) that provide different
controlling forces have different degrees of
stiffness.
15. The bridging device according to claim 14,
characterized in
that the spring devices (11) that have different
degrees of stiffness have a different number of
identical spring units.
16. The bridging device according to claim 14,
characterized in
that the spring devices (11) that have different
degrees of stiffness comprise different spring units
(12) with differently steep force-displacement
characteristics.
17. The bridging device according to claim 16,
characterized in
that the spring units that have differently steep
force-displacement characteristics have a different
number of identical spring elements.
18. The bridging device according to one of claims 1 to
13,
characterized in
that the spring devices (11) that provide different
controlling forces have spring units (12) that are
pretensioned to different degrees.
19. The bridging device according to one of claims 1 to
18,
characterized in

19
that, with a maximum joint width, the controlling
force of the spring device comprising the maximum
controlling force is at least 1.7-fold the
controlling force of the spring device comprising
the minimal controlling force.
20. The bridging device according to one of claims 1 to
19,
characterized in
that the spring devices (11) comprise spring
elements (15) that are designed as elastomer springs
(16).
21. The bridging device according to one of claims 1 to
20,
characterized in
that the spring units (12) of two adjacent spring
devices (11) are structurally coupled.
22. The bridging device according to claim 21,
characterized in
that the spring units (12) of two adjacent spring
devices (11) are coupled in each case via a plate
(13, 17) that is rigidly connected with the middle
one of three adjacent slats (7) with both adjacent
slats being connected to the plate (13, 17) via
spring elements (15).
23. The bridging device according to one of claims 1 to
22,
characterized in
that the spring devices (11) comprise spring units
(12) that, in each case, are placed on a number of
control bays that are placed in each case between
two adjacent cross-members (5), whereby abrupt
increases in the controlling force within the

control chain of the individual control bays are
offset to one another in the different control bays.

The invention relates to a bridging device for an expansion joint (4) in a structure fit for traffic, said expansion joint
being placed between an abutment (2) and a superstructure (3). A number of cross-members (5) that bridge the joint gap extend
between the abutment and the superstructure and are supported on the abutment and on the superstructure. A multitude of slats
(7) extending in a longitudinal direction of the gap are placed between the abutment and superstructure and are each supported on
at least one portion of the cross-members. The distance of the slats from one another is controlled by spring devices to which the
relevant slats are connected. The individual spring devices provide different controlling forces according to their arrangement inside
the device, whereby the respective controlling force of the spring devices has a gradient transversal to the longitudinal direction of
the joint.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=nz9txihO1QktU2ARe2sZXg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

271519

Indian Patent Application Number

2758/KOLNP/2007

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

24-Feb-2016

Date of Filing

26-Jul-2007

Name of Patentee

MAGEBA S.A.

Applicant Address

SOLISTR. 69, CH-8180 BULACH

Inventors:

#	Inventor's Name	Inventor's Address
1	URICH, BERND	WILDSTR. 12, CH-8193 EGLISAU

PCT International Classification Number

E01D 19/06

PCT International Application Number

PCT/EP06/000135

PCT International Filing date

2006-01-10

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	05000533.9	2005-01-12	EUROPEAN UNION