This invention relates to railway installations, and in particular to rail damper structures for reduction of rail vibration and noise generated from the railway.
Over the past two decades, railway dampers have been widely used to reduce railway noises in newly developed railway lines and as an improved noise reduction measure in operating railways. Rail dampers are generally designed to cover a large surface area on rail foot and rail web at both sides of the rail by a thin layer of resilient interface material. However, track engineers would like to have clear views on the rail surface during routine maintenance inspections. A rail damper with a small contact area on the rail is needed so that more rail surface is visible during routine maintenance inspections.
For safety concern on rail integrity, bolts through rails are normally not allowed for mounting of rail dampers. Adhesives on the other hand normally cannot provide a rigid connection for retrofitting dampers onto operating rails due to adhesive resilient property, uncontrolled rust surface and unknown profile tolerance.
In the railway industry, spring clips with hooks (sometimes also with adhesive applied at the interface between the damper and the rail) is a common method for installation of rail dampers. However, mounting clips with a hook in conventional designs cannot utilize its maximum clipping force because the installation process always exerts additional stress on the clip during the locking process of the hook.
When the Tuned Mass Damper (TMD) type of rail dampers vibrates with the rail, its reaction damping force is amplified to several times its weight. A higher TMD amplification factor provides a higher damping force at a frequency-narrower bandwidth, but it also requires a higher mounting force. Rail damper mounting clips in conventional designs (even with the adhesive applied) cannot provide sufficient mounting force to overcome the amplified TMD reaction force. In general, mounting force is required to be more than 1 ton per damper in the case of a strong rail vibration (˜50 g rail vibration acceleration after damper installation; for example, a 300 g rail vibration being reduced to around 50 g by the damper installation). Clips currently used in the industry only provide a mounting force up to a few hundred kilograms per damper. Existing rail dampers would be temporarily disengaged from the rail by a few micrometers (or fractions of micrometers) in case of a strong rail vibration due to insufficient mounting force to overcome the acceleration force at peaks of oscillation cycles.
An improved design of the damper mounting clip is, therefore, required to avoid applying additional stress to the mounting clip during damper installation. In addition, a mounting clip with a higher mounting force is desired.
Accordingly, the present invention, in one aspect, is a rail damper mounting apparatus that contains a clipping device adapted to clip onto a rail, and a mounting device adapted to allow an oscillator to secure thereto. The rail damper mounting apparatus forms at least three clipping points with a rail when the rail damper mounting device is installed to the rail.
In some embodiments, the mounting apparatus forms two clipping points located above a plane defined by foot tips on of the rail on two sides of the rail, and one clipping point below the plane, when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the clipping device contains a rail web contact member and a rail foot contact member. The rail web contact member forms respectively a first clipping point and a second clipping point above the plane at a foot and a web of the rail respectively, when the rail damper mounting apparatus is installed to the rail. The rail foot contact member forms a third clipping point below the plane at the foot of the rail.
In some embodiments, the rail web contact member has a side edge in a curved shape that faces the web of the rail when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the rail web contact member is formed as a single piece with the rail foot contact member. The side edge forms the first and second clipping points when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the rail web contact member is formed as a single piece with the mounting device, where the side edge at least partially follows the contour of an oscillator installed to the mounting device.
In some embodiments, the first and second clipping points are located on the side edge at substantially the same radial distance from a rotating center defined by an intersection of two lines respectively normal to tangential lines at the first and second clipping points.
In some embodiments, the mounting apparatus forms one clipping point located above a plane defined by foot tips of the rail on two sides of the rail, and two clipping points below the plane, when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the clipping device includes a rail foot contact member and a hook member. The rail foot contact member forms respectively a first clipping point and a second clipping point with the foot of the rail, when the rail damper mounting apparatus is installed to the rail. The hook member forms a third clipping point with the foot of the rail.
In some embodiments, the rail foot contact member and the hook member are located on the two sides of the rail, and are connected through an extension arm that runs parallel to a bottom face of the foot of the rail when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the hook member forms an inward tip which is adapted to contact the foot of the rail to form the third clipping point.
In some embodiments, the hook member includes a hook portion having an opening substantially toward a direction away from the foot of the rail when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the hook member contains a hook portion having an opening substantially toward an opposite direction to that of the recess of the hook member.
In some embodiments, the extension arm is at least partially resilient so that the clipping device can be clipped onto the rail by moving the hook member in a direction substantially perpendicular to a longitudinal direction of the extension arm using an external tool.
In some embodiments, the rail foot contact member contains a slot for receiving the foot of the rail from a side direction. The second clipping point is formed between a bottom face of the foot of the rail and the slot when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the second and third clipping points are located at the bottom face of the foot of the rail when the rail damper mounting apparatus is installed to the rail.
In some embodiments, the mounting device has a plate shape. The mounting device is adapted to allow two oscillators to secure thereto at two sides of the plate shape.
In some embodiments, the rail damper mounting apparatus is adapted to be connected to a similar rail damper mounting apparatus on an opposite side of the rail by an extension arm.
According to another aspect of the invention, there is disclosed a rail damper system containing a plurality of rail damper mounting apparatus as mentioned above, which are installed to a railway, and oscillators installed to each rail damper mounting apparatus. The plurality of rail damper mounting apparatus is positioned along a longitudinal direction of a rail, and/or positioned symmetrically on two rails of the railway.
There are many advantages to the present invention. Firstly, with at least three clipping points/areas with the rail formed by each rail damper mounting apparatus, it provides a strong clipping force compressing the wedge-liked rail foot by a very stiff clip, where the bending stiffness of the clip at the top surface clipping point/area is roughly in the order of a fraction of a ton per millimeter to a few tons per millimeter. A strong clip compression force is applied to the foot of the rail to ensure a rigid connection for vibration energy transmission from the rail to the oscillator (e.g. a TMD oscillator) for dissipation.
In addition, the rail damper mounting apparatus has a modular design, which means that each such apparatus is independently installed onto a rail, or two rails of a railway, such that the number of mounting apparatuses can be adjusted flexibly to suit the site conditions. The repetitive modular design simplifies rail damper assembling process and enhances large scale production for cheaper manufacturing. In this way, any desired length between the sleeper spacing of the rail may be equipped with the rail damper mounting apparatuses according to the invention, and these rail damper mounting apparatuses together form a rail damper system. In one example of the rail damper system, pairs of rail damper mounting apparatuses can be installed symmetrically on one of the two rails of a railway, along the length of the railway. In another example of the rail damper system, pairs of rail damper mounting apparatuses can be installed symmetrically on each rail of a railway so that along a lateral direction of the railway there are in total four damper mounting apparatuses installed.
The design of the rail damper mounting apparatus with a small area at the contact interface provides fewer obstructions to the inspecting staffs for routine visual inspections maintenance comparing with conventional rail damper products in the market.
According to some embodiments of the invention, the number of dampers installed on each rail can be chosen from only one to a few (for example, it can be 1, 2 or 3 oscillators), and for example oscillators can be connected to two sides of a circular mounting device in the form of a plate. Such a mounting device is a metal plate without a joint, which is integrated with a stiff clipping device (and sometimes also including an integrated hook member). The clipping device contains a rail foot contact member (and sometimes also including a rail web contact member) that provides a strong vertical mounting force when it is dragged by a horizontal force by the hook member pulling (or pushing) the rail foot contact member into a wedge-shaped rail foot tip. The clipping device is maintained at the clipping location by a horizontal pulling force by a locking hook hooked to the other side rail foot tip.
The foregoing summary is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
The foregoing and further features of the present invention will be apparent from the following description of embodiments which are provided by way of example only in connection with the accompanying figures, of which:
In the drawings, like numerals indicate like parts throughout the several embodiments described herein.
In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
As used herein and in the claims, “couple” or “connect” refers to electrical coupling or connection either directly or indirectly via one or more electrical means unless otherwise stated.
Terms such as “horizontal”, “vertical”, “upwards”, “downwards”, “above”, “below” and similar terms as used herein are for the purpose of describing the invention in its normal in-use orientation and are not intended to limit the invention to any particular orientation.
To achieve a robust clipping effect for the rail damper mounting apparatus, a third clipping point is required beside the first clipping point 26a and the second clipping point 26b. The third clipping point 26c is located far away from the clipping device 22, as it is formed at the contact point between an inward end tip of a hook member 24 and a side of the foot 20c of the rail 20. The hook member 24 is designed to hook on the end of the foot 20c opposite to the one to which the clipping device 22 is clipped onto. In particular, the hook member 24 is to be hooked to a tip of the foot 20c at the other side of the rail 20 in order to provide a tension force for preventing the clipping device 22 from slipping off the foot 20c. The hook member 24 is curved inwardly (i.e. toward the foot 20c of the rail 20) to form the inward tip, but the hook member 24 further extends outwardly from the inward tip in the direction substantially away from the foot 20c of the rail 20 to form a hook portion 24b. The hook portion 24b is substantially along a vertical direction (i.e. perpendicular to the bottom face of the foot 20c) and is intended to complete the clipping process of the rail damper mounting apparatus to the rail 20 by the user using an external tool as will be described later. As one can see from
The hook member 24 is connected to the clipping device 22 via the extension arm 28 where the three are formed as a single piece. The extension arm 28 has a thinner cross-section than that of any portion of the clipping device 22, in order to allow flexible movement of the extension arm 28 along the vertical direction while applying only minimal additional stress to the clipping device 22 (e.g. less than 1% of the yield stress of the clipping device 22). Besides, the flexibility in vertical movement of the hook member 24 is an important feature in the installation process such that the frictional force at the clipping locations at the wedge-shapes foot 20c of the rail 20 would be strong enough to prevent the clipping device 22 from slipping back during the clipping process. That is, during the pulling (or pushing) of the clipping device 22 into the wedge-shaped foot 20c, the clipping device 22 does not immediately slide back when the pulling force stops. However, if the flexibility of the vertical movement is not enough, the clipping device 22 would immediately slide back once the pulling (or pushing) force stops during the installation process. As shown in
It should be noted that an oscillator or its mounting device is not shown in
Turning to
Turning to
To install the rail damper mounting apparatus, the user first need to inserts the slot 130 of the clipping device 122 into one end of the foot 120c of the rail 120. When the clipping device 122 is installed fully by pressing it to the maximum extent toward the foot 120c, a first clipping point 126a and a second clipping point 126b will be formed, which are located at the same positions as mentioned for those in
a,
4
a and 5a show the status where the level bar 144 has not engaged with the hook member 124. To hook the hook member 124 to the foot 120c, the user insert the anchor pin 146 into the recess of the hook portion 124b of the hook member 124, and at the same time a concave part 144c of the curved member 144b is pressed against an side face of the foot 120c, as shown in
Turning to
Below the mounting device 432 there is integrally formed a clipping device 422 which defines a slot 430 for receiving one end of the foot 420c of the rail 420 from a side direction. Unlike the case in
Turning to
The exemplary embodiments are thus fully described. Although the description referred to particular embodiments, it will be clear to one skilled in the art that the invention may be practiced with variation of these specific details. Hence this invention should not be construed as limited to the embodiments set forth herein.
While the embodiments have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
In the embodiments mentioned above, each rail damper mounting apparatus contains a single piece of mounting member in a plate shape. However, a variation of the preferred embodiments could be that the mounting device is formed by identical two mounting members of the same shape, but each with half the thickness of a mounting device in the embodiments described above. The two half mounting devices are jointed together by the compression force exerted on the resilient materials on both side of the mounting devices. This arrangement provides a better balanced mounting force by allowing relative movement between the two mounting members during the damper installation on uneven mounting surfaces. The thinner half-thickness mounting device design also facilitates the manufacturing process by using laser cutting.
In the embodiments described above, the clipping device as a plate-like piece is directly made into contact with the wedge-liked rail foot. However, those skilled in the art should realize that the clipping device may also be made into indirect contact with other material or member at the interface.
In the embodiments, the rail that the rail damper mounting apparatus is suitable to use with has a flat-bottom profile which is common in most modern railways. However, one should realize that other types of rails may also be suitable to be used by the rail damper mounting apparatus according to the invention which may have different cross-sectional shapes.
In the embodiments mentioned above, one to two oscillators are installed on each rail damper mounting apparatus. However, it should be realized that any number of oscillators may be installed on a rail damper mounting apparatus depending on the type and number of mounting devices.
Filing Document | Filing Date | Country | Kind |
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PCT/CN2021/088495 | 4/20/2021 | WO |
Number | Date | Country | |
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63016312 | Apr 2020 | US |