EP1015697A1

EP1015697A1 - Isolating and dampening rail for railbound traffic

Info

Publication number: EP1015697A1
Application number: EP98930018A
Authority: EP
Inventors: Bengt BÖNSTRÖM
Original assignee: Cito Trading Co
Current assignee: Cito Trading Co
Priority date: 1997-06-19
Filing date: 1998-06-22
Publication date: 2000-07-05
Also published as: SE9702375D0; AU7950098A; WO1998058126A1; SE9702375L

Abstract

The invention relates to an arrangement for insulating and damping rails for trackbound vehicles. Damping is imparted through interaction partly through contact between the rail (20) and a central rail foot spreader (1) on each foundation (3), partly through the damping of vertical accelerations via pre-tensioned sleeper clips (4) acting symmetrically in the y-axis, and partly through direct contact between the rail and the foundation (20, 3) - contact damping. Said foundation (3) in the unloaded condition exhibits contact symmetrically in pairs about the y-axis with the rail (20) via the pads (5) furthest away from the y-axis exhibiting on or symmetrically about the y-axis existing sleeper clips (4) in contact with the central part (1) permanently pre-tensioned to the foundations and exhibiting said central part (1) suitably tightened to the rail foot via rail foot spreader clips (2).

Description

Isolating and dampening rail for railbound traffic.

A rail attached to a foundation (sleeper, etc.) is subjected to dynamic stresses under trackbound traffic. These dynamic, varying stresses induce kinetic energy in the rail body. This kinetic energy should be minimized and otherwise dealt with (converted into heat) rapidly. The constituent component parts of today's tracks in themselves possess low hysteresis, and even the pre-stressed concrete sleeper rings like a church bell when exposed to shocks and impact forces. As a result, when the undamped system is exposed to kinetic energy, the system in use today calls for powerful, sustained vibration conditions in order to convert this energy, in the course of which disturbing interferences and by-products, such as noise and carcass vibrations (noise), affect the immediate environment.

The reinforcement has a number of functions, and the rail shall be:

Satisfactorily located in three planes (X, Y, Z) , and around its longitudinal axis of rotation, at the same time as which a number of degrees of freedom (elasticity) are assured. The x-axis lies in the longitudinal direction of the rail, the y-axis in the transverse direction of the rail, and the z-axis in the vertical direction of the rail.

More recent requirements for a better environment and less noise and vibrations impose different priorities than previously. Priority was previously given to sub- optimizations as the lowest possible installation cost. The rail is today fixed with "clips", which are compromise products containing a number of functions. In order to optimize a product in accordance with today's requirements, it is necessary to separate and structure "basic" functions, to subdivide them into different separate components, to reduce the degrees of freedom which they provide in certain areas, and to increase others so that the "basic" functions are assured, at the same time as new functions are provided in accordance with the heading.

In the accompanying drawings,

Fig. 1 shows a fixing position in the left part, whereas the right part shows a transport position of a means of track damping that is transportable from the factory to the laying site, viewed in the longitudinal direction and from above;

Fig. 2 shows a section through part of the damping along the y-axis;

Fig. 3 shows a sectioned view through the damping;

Fig. 4 shows a side view of the damping;

Fig. 5 shows an upper and a lower sectioned view of the damping;

Fig. 6 shows a perspective view of the damping in the installed position;

Fig. 7 shows the damping laid loosely on a base; and

Fig. 8 shows the under side of the damping.

The new product in accordance with the invention consists of rail foot spreaders on each foundation 3, e.g. sleepers. The rail foot spreader is formed from two "clips" 2 attached to the actual rail foot spreader 1. The clips are retained securely with screws or bolts or the like in the spreader in contact with the rail foot, so that a satisfactory frictional joint is obtained between the spreader and the rail, at the same time as the rail creep arrester (x-axis) is constituted.

The traditional other clip function and rotation and lifting arrester (y-axis) are constituted by two separate bolted or screwed symmetrically located rail/sleeper clips 4, to either side of the rail 20, which are permanently attached to the foundation 3 and are in contact with the rail foot 21 and with the projecting part of the rail foot spreader. The necessary degrees of freedom in other respects and the attachment y- and z-axes) are provided by elastomers (rubber, etc.) (5) in the form of an insert between the rail foot/rail foot spreader and the foundation.

The functions outlined above are used to create a new product with new functions, which are well defined and have a comparatively low manufacturing cost, that can be made available to customers who administer tracks with existing rail sections and integrated into existing tracks. Both insulation and damping are provided. The disturbing ground and building vibrations, as well as the disturbing rail/wheel airborne noise ' that we encounter today, present considerable control difficulties and relate to a few limited frequency areas.

One of these is the "pin-pin" frequency with a wavelength corresponding to twice the distance between the foundations along the length of the rail.

A product of the kind outlined above makes available an attachment that provides damping of rotational vibrations about the y-axis of the foundations (e.g. of the "pin-pin" type described above) . This is not the case with present-day attachments. Damping in the z-axis is today provided only via "pads", whereas the clips are steel springs. Furthermore, pads and clips with minimal damping characteristics are both centrically located directly above one another in the XYZ-axis of the foundations. A product of the kind outlined above also permits contact forces in the z- axis to be manipulated to a considerable extent; for example, relative manipulation of the contact pressure of the sleeper clips against the rail foot and against the rail foot spreader is possible. The use of an appropriate design for the rail foot spreader also offers the possibility of damping internal contact between the rail head and the rail foot, which closely follows the "whole body" (external) movements of the rail body. The present product has divided up the functions in such a way that the clips and pads lie separately in the z-axis during the particular loading phase of the foundations, which is by far the most common, namely when the rail is not under load or is loaded under the maximum working load (S L) .

During the loading phase, when the rail is loaded to its maximum SWL, the pads are loaded over their entire extent in the x-axis. The clips, on the other hand, are not under load at this time. The pre-load in the sleeper clips is then relieved by the wheel, which is permitted in the present system by the fact that the basic functions of the clips are separated and, for example, the tendency of the rail to creep is counteracted satisfactorily and constantly by the rail foot spreader. The damping provided by the clips is also not needed during this phase (the wheel assumes this function) . The system comprising the rail, sleeper and foundation in the sleeper-in-ballast type of track is damped in this phase through assured good contact between the foundations and the ballast. In the case of foundations on a solid base, e.g. a bridge, damping is not fully prioritized within all the frequency ranges during this phase, but primarily the insulation. In order to prevent sympathetic vibrations in the bridge, for example, the centre-to-centre distance of the foundations and their relative positioning are manipulated there to the desired extent. (Marching in step on the bridge must be avoided ...) .

This combined, short-duration phase (maximum loading) in the total service life of the reinforcement is also not a problem as far as today' s track technology is concerned. The problem is "restricted" to the "residual phase" - the phase that entirely dominates the life cycle of the track. The unloaded, rolling wheel with its tendency to "bounce" on the rail, especially over foundations with little flexibility, is encountered here, for example. This tendency is reduced by the present product, thanks to the fact that the degree of freedom relating to the elasticity (springing) of the pads can be maximized in turn thanks to the fact that the degree of freedom relating to the clips is minimized accordingly. Any tendencies of the rail to creep are satisfactorily restricted at the same time without the need for anything other than negligible pre-loading of the sleeper clips and the pads. Thanks to this characteristic, full use can be made of the elasticity of the pads (it is not taken into account more than minimally, and it is negligible due to the pre-loading of the sleeper clips) . This is essential for insulation.

In order to damp any internal rotational vibrations in the rail about its longitudinal axis x, it shall be possible for notches to be provided in the rail foot spreader of the present product for the attachment of contact dampers (brackets on one side or symmetrically to the x-axis on each foundation 6) . The sleeper clips shall be similarly capable of being provided with a notch for the attachment of supports for damping external ditto (whole rail body) 7. In those cases in which the foundation comprises sleepers lying in macadam, it shall be possible for two or more of these to be connected together by means of separate connections and symmetrically to the x-axis of the rail and the longitudinal rail 8, in order to provide damping for any sleeper/sleepers that are not in contact with macadam ("hung sleepers") . This connection is present automatically, for example, in foundations on a solid base, where the presence of "hung" sleepers is also not envisaged. In order to permit rapid installation of the product, the sleeper clips and the rail foot clips shall be integrated in such a way that the rail foot spreader clips are screwed loosely in position when the sleeper arrives at the site of installation, but are appropriately attached by elastomer concentrically to the associated screw in the raised position. The entire package consisting of the rail foot spreader and the two sleeper clips is appropriately retained on the sleeper during the transport phase. When the rail is in position in the rail attachment, the sleeper clips are introduced into their fixing position, and their screws are tightened to provide permanent fixing of the sleeper clips to the foundation. The rail clips then accompany this lateral movement, and their screws are tightened so that the rail foot clips and the rail foot spreader together with the rail foot itself form an integral part that slavishly follows the movements of the rail foot, but with a certain freedom of movement between the rail foot/rail foot spreader along the rail, at the same time as this movement is constantly and satisfactorily restrained by the degree of tightening of its screws .

The fact that the sleeper clips "support" the rail foot spreader clips in conjunction with the fixing movement means that the relative lateral position is retained between these two components, so that a suitably adapted elastomer positioned on the side at the utilization stage can then transfer elastic lateral forces from the rail foot via the spreader, via the elastomer and via the sleeper clips to the foundation that is permanently attached to the sleeper clips.

The function is further assured by the fact that the rail foot spreader lies in a recess in the foundation with space beneath and to the sides of the rail foot spreader. In this way, degrees of freedom are created for relative movements between the rail and the foundation. The recess in the foundation for the rail foot spreader can be expected to exhibit a greater depth than the support surfaces for pads situated symmetrically on the rail foot spreader. The aforementioned recess should, therefore, exhibit drainage holes passing through the base of the foundation. To the extent that the upper load-bearing surface for the aforementioned pads is bounded by upward-projecting lateral edges, its lateral edges must be perforated to permit the aforementioned drainage and to enable the pads to be produced in a continuous piece joined together by elastomer and "fitting" into the aforementioned recesses. Because greater priority is given in accordance with the foregoing to the function of the unloaded or slightly loaded track than with today' s technology, it is necessary for the unloaded sleeper to be damped. This must be assured by means of contact damping. Sleepers lying relatively close together must be used, with a centre-to-centre distance of approximately 500 mm, and with the smallest possible necessary contact surface with the ballast bed. In the case of uneven movements of the ground and resulting induced high dynamic stresses in the ballast beneath supporting sleepers, the ballast must be redistributed by the effect of the traffic so that any areas of unevenness along the track are automatically adjusted. Contact damping between sleepers shall also be assured by mutual attachments 8 between sleepers in accordance with the above. These attachments shall exhibit a small or elastic contact surface with the ballast, although they may also provide the base for a "mat" 9, which in turn supports ballast lying on top of the mat. A mat of this kind shall be positioned in such a way as not to prevent the use of the customary ballast packing equipment. A "mat" of the kind described above shall, for example, provide damping of movements in the track in the case of "hung" sleepers and in the case of lifting 10 to either side of a wheel under load. Although all tracks in principle exhibit the same basic function, a distinction is made between tracks on a permanent base and tracks on ballast. In order to be able to manage these types of base satisfactorily in terms of insulation and damping from a track engineering point of view, it is necessary to structure the functions and to take account of common features.

The ballast exhibits elastic properties, for example, and contributes both insulation and damping. A permanent bed is present in turn beneath this ballast bed. In order to be able to use the same technology, therefore, present-day technology requires the presence beneath the foundation (sleepers) , for example on a bridge, either of ballast as described above or, for example, an elastomer (boots) . In order to be able to comply closely with present- day construction engineering requirements, an entire' range of measures is needed, many of which are shown below to be unique and to possess a level of invention in their own right. Application for a patent is accordingly made both for the system and for its associated components. To the extent that components may appear to be previously disclosed, this may be attributable to similarities. This is in the nature of things, in order not to deviate from the quite narrow "basic" functional requirements that must always be set for railway tracks. The priority nevertheless differs from what was indicated by way of introduction, which means that entirely unique characteristics are exhibited.

The foundation 3 for the rails for a trackbound vehicle exhibiting x-, y- and z-axes, in which a form or function is exhibited to either side of the y-axis such that, when the rail 20 is fixed and in its unloaded phase, the rail is supported symmetrically against that part of the foundation 10 that that is present along from the y- axis, exhibiting sleeper clips 4 capable of being tightened securely to the foundation, symmetrically about the x-axis and about or on the y-axis for simultaneous satisfactory tightening to the upper surface of the rail foot and/or to a separate rail foot spreader concentric with the y-axis exhibiting a central part 1, in turn through separate rail foot spreader clips 2, tightened to the rail foot and thus integrated with it, in which said clips 2 exhibit in their vertical projection a projecting profile relative to the central part 1, where the central part 1 and the rail foot spreader clips 2 together constitute the rail foot spreader. Said sleeper clips 4 exhibit pairs of oval holes, extended in the y-axis so that, with the foundation 3 in the pre-assembly phase, the clips can be temporarily fixed in a side position to the y-axis so that the rail 20 can be lowered into the foundation 3 without being obstructed by the sleeper clips 4 for final fixing by moving the clips in the y-axis into the fixing position, where they are pre-¹. tightened/tightened to the foundation to achieve satisfactory fixing with the help of pre-tightening arrangements passed through the aforementioned holes, exhibiting contact in the y-axis via an interjacent elastomer (pad) 11 with a separate rail foot spreader clip 2, which, thanks to corresponding oval holes 30, is similarly manoeuvred automatically through the lateral movement of the sleeper clips over the rail foot into the fixing position unobstructed by its own separate fixing arrangement thanks to the aforementioned elastomer 11.

The foundation, support and fixing clips are mutually arranged so that, when the support is unloaded, the contact surfaces between the rail foot and the pad 5 or the clips are separated from one another in a plane so that all of them lie symmetrically above the y-axis of the foundation and are arranged so that the rail foot spreader clips 2 lie concentrically, and the others lie symmetrically to either side of the aforementioned y-axis with the vertical contact supports 10 of the pads only outermost in this phase (furthest away from the y-axis) . The pads 5 exhibit projecting contour lines in their vertical projection outside the supported surface of the rail or the rail foot spreader. Said contour line constitutes part of a boundary surface with a trapezoidal form (12) in its vertical section formed by, for example, a recess in the foundation, where the pads exhibit the same trapezoidal form. Said rail foot spreader surface in turn exhibits similar trapezoidal form in contact with the pad. The rail foot spreader exhibits an attachment notch for a contact damper 6 supported against the upper part of the rail, either metal or a membrane.

The foundation shall exhibit direct attachment in pairs in at least one direction (x or y) 8. Such attachment in the x-axis shall exhibit an axis of symmetry coinciding with the x-axis and shall act in a plane with the lower boundary surface of the foundation.

The foundation shall exhibit two separate recesses 14, which shall be symmetrical about the x-axis, which are partially covered in the y-axis by sleeper clips in the fixing position.

The principal idea of invention is for the rail foot 21 to be supported against the rail foot spreader 22 formed by a metal sheet and with damping in a downward direction by an elastic element 23 on its under side, in conjunction with which rows of projecting tops 24 are able to form such elastic elements. The rail foot 21 is supported only against two elastic elements 24 displaced at a mutual distance from one another viewed in the y-axis along the longitudinal direction of the rail.

Claims

P a t e n t C l a i m s

1. Arrangement for rails (20) for trackbound vehicles in which, both in the unloaded and in the loaded condition, damping (hysteresis) is imparted through interaction partly through contact between the rail (20) and a central metallic rail foot spreader (1) on each foundation (3), partly through the damping of vertical accelerations (z- axis) via pre-tensioned sleeper clips (4) similarly passing centrally and horizontally across the rail (20) and acting symmetrically in the y-axis, and partly ditto through direct contact between the rail and separate elastic pads (5) to either side of that central part, which pads are so arranged as to be pre-tensioned with the minimum force necessary to ensure contact between the rail and the foundation (20, 3) (contact damping) , in conjunction with which the foundation (3) , viewed in the x-, y- and z-axes, is defined by the longitudinal direction of the track (x-axis), across the track (y-axis) , and in the vertical direction of the track (z-axis), characterized in that the foundation (3) in the unloaded condition exhibits contact symmetrically in pairs about the y-axis with the rail (20) via the pads (5) furthest away from the y-axis exhibiting on or symmetrically about the y-axis existing sleeper clips (4) in contact with the central part (1) permanently pre-tensioned to the foundations and exhibiting said central part (1) satisfactorily tightened to the rail foot, via bolted or screwed rail foot spreader clips (2) .

2. Arrangement as claimed in Patent Claim 1, characterized ┬▒n that the foundation (3) exhibits sleeper clips (4) and pads (5) displaced in pairs symmetrically about the y-axis, along the x-axis, acting in a direction towards one another against the rail foot spreader and against the rail, in the unloaded phase, so that their resultants lie displaced along the x-axis with the sleeper clips (4) acting centrally symmetrically about or on the y-axis and the pads (5) symmetrically about the y-axis peripherally with both acting in the z-axis.

3. Arrangement as claimed in one or other of Patent Claims 1-2, characterized in that the foundation (3) exhibits a central part with the rail foot spreader (1) projecting outside the foot of the rail exhibiting surrounding elastomers in contact with the foundation in the x-, y- and z-axes.

4. Foundation in accordance with one or other of Patent Claims 1-3, characterized in that contact surfaces between elastomers, the foundations and the rail foot spreader exhibit trapezoidal form (12) with a cross-section of decreasing extent (x and y-axis) in the downward sense, so that elastomers in the vertical projection exhibit projecting contour lines outside the surface of the supported rail and rail foot spreader, and in that these projecting elastomers at the top are at least partially supported against the under sides of the clips.

5. Arrangement in accordance with one or other of Patent Claims 1-4, characterized in that a central part (1) exhibiting a rail foot spreader and two existing rail foot spreader clips (2) symmetrical with the x-axis together form the rail foot spreader, and in that the rail foot spreader clips, when they are tightened to the rail foot, exhibit a projecting profile in the x and y-axis in relation to the central part.

6. Arrangement in accordance with one or other of

Patent Claims 1-5, characterized in that said foundation in the transport position has sleeper clips and rail foot spreader clips temporarily installed in a lateral position so that, when the rail is placed in the foundation, both clips are subjected to a lateral movement (y-axis) into the fixing position, in which they are tightened to the foundation and the central part, both unobstructed by their separate fixing arrangements, in that the sleeper clips (4) exhibit pairs of oval holes extending in the y-axis, and exhibiting contact in the y-axis via interjacent elastomers (11) with separate rail spreader clips (2) exhibiting corresponding oval holes, and in that the foundation has a recess (14), which is partly covered in the y-axis by sleeper clips in the fixing position.

7. Arrangement in accordance with one or other of

Patent Claims 1-6, characterized in that, for the purpose of providing damping of the vertical accelerations of the track through pairs of mutual connections in at least one direction (x or y) , the connection in the x-axis exhibits an axis of symmetry coinciding in its vertical projection with the x- axis of the foundation in the vertical sense, situated on the lower boundary surface of the foundation.

8. Arrangement in accordance with one or other of

Patent Claims 1-7, characterized in that the rail foot spreader is executed for damping of rotational vibrations of the rail head in that the rail foot spreader exhibits an attachment for a contact damper (6) supported against the upper part of the rail.