Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
  • E01B19/00—Protection of permanent way against development of dust or against the effect of wind, sun, frost, or corrosion; Means to reduce development of noise
  • E01B19/003—Means for reducing the development or propagation of noise

Definitions

• the present invention relates to rail fixings. It is more particularly concerned with rail fixings that exhibit advantageous noise characteristics.
• the noise emitted by moving rail vehicles is a major limitation on their use, in that it will limit the ability of operators to install new lines in populated areas, and will limit speeds and traffic volumes on existing lines.
• the noise tends to be dominated by rolling noise from the wheel/rail interface, which is caused partly by vibration of the wheels and partly by vibration of the track.
• the present invention seeks to provide a means for reducing the track noise emitted by a rail system. It therefore provides a damper for a rail, comprising at least one deformable material attachable to a surface of the rail and incorporating a plurality of elongate resonant members, the resonant members being of a stiff material as compared to the deformable material and being sized to form a resonant system with at least two resonances in the frequency range where rail vibration is to be reduced.
• the resonant members are of different profile, as this provides an easy way of tuning to two different frequencies. However, this can still be achieved with identical profiles. They are suitably embedded in the deformable material, as this both ensures adequate vibrational transfer from the rail to the resonant members and also provides environmental protection. They are ideally more dense than the resilient material. They are suitably of steel or other dense material.
• the deformable member is preferably visco-elastic, for example rubber or a rubber-like material. This may be preformed and glued to the rail, or it can be cured in place on the rail.
• the damper is positioned on the rail so as to cover the junction between the web and the foot of the rail. This has been found to be exceptionally advantageous in terms of the amount of damping needed to achieve adequate noise reduction.
• a damper with at least two resonant frequencies according to the invention can reduce significantly the noise level of the rail.
• One resonant member can be a elongate angled section, the angle preferably matching the angle between external surfaces of the head and foot.
• Another resonant member can be a solid elongate block, the external faces adjacent the web and foot being angled to match. Further resonant members can be employed as necessary.
• the damper will be easier to manufacture and easier to apply to existing rail if the resonant members are discontinuous within the deformable material. Ideally, the discontinuities in the plurality of resonant members will coincide. It is also possible to apply the damper in discrete sections, leaving gaps (for example) for rail fasteners. However, a continuous length of damper is preferred. It is preferable for there to be a pair of such dampers, one either side of the rail.
• Figure 1 is a vertical section through a rail incorporating dampers being a first embodiment
• Figure 2 is a vertical section through a rail incorporating dampers being a second embodiment.
• Figure 1 shows a vertical section through a rail 10 fitted with a damper according to the present invention.
• the rail 1 0 comprises a head 1 2 which carries the traffic and a narrower web 1 4 extending downwardly from the head 1 2 to a foot 1 6, generally wider than both the head 1 2 and web 14, on which the rail section rests. In this respect it is a standard rail section.
• the junction between the web 1 4 and the foot 1 6 is smoothed for fatigue reasons (amongst others), but is essentially a transition from a substantially vertical face to a gently downward sloping top surface of the foot 1 6. Thus, the angle is somewhat over 90° , usually in the region of 1 20° .
• each damper comprises a block of rubber 20 in which is embedded a first resonant member 22 and a second resonant member 24.
• the first resonant member is an elongate angled member, the angle corresponding to the junction between the head and foot.
• the second resonant member is an elongate solid section, positioned in the angle of the first and with two faces at a corresponding angle. The mass per unit length of the first member is greater than the others, significantly so.
• the resonant members are discontinuous to allow the damper section to be cut. This eases application of the damper to rail.
• a suitable maximum length for the sections is 1 metre for application to existing rail.
• the top surface of the damper 1 8 can be profiled to prevent water from building up and seeping into the system.
• This arrangement of dampers provides a particularly compact arrangement which is nevertheless able to absorb a wide band of frequencies efficiently from the rail.
• This frequency band which may be different for vertical and lateral vibration of the rail, is determined by the resonances of the damper. These resonances are controlled by the choice of mass per unit length of the resonant members and by the surrounding geometry and the physical properties (principally the stiffness) of the material between the resonant members.
• the width of the frequency band is also determined by the damping properties of the visco-elastic material in the interlayers.
• the visco-elastic provides a support medium for the resonant members and by its damping , properties dissipates vibrational energy.
• FIG. 2 shows a second embodiment of the present invention. Most features of the second embodiment are identical to the first and have therefore been indicated using identical reference numerals. The second embodiment differs only in the construction of the dampers.
• first, second and third resonant members 26, 27 and 28 are provided. All three in this embodiment consist of an angled metallic member. Each are of different external dimensions so as to resonate at different frequencies. The three are nestled within each other and within the rubber block 20.
• dampers of the present invention could be applied in conjunction with known resilient rail fasteners. This would enable the other advantages of resilient fasteners to be achieved without an unacceptable increase in noise.
• resonant members could be arrange end-to-end instead of adjacent as illustrated. They would then be in the same mass of deformable material or in adjacent masses.

Landscapes

• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Railway Tracks (AREA)
• Vibration Dampers (AREA)
• Vibration Prevention Devices (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Liquid Crystal Substances (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Coupling Device And Connection With Printed Circuit (AREA)
• Inspection Of Paper Currency And Valuable Securities (AREA)
• Chain Conveyers (AREA)
• Fuel-Injection Apparatus (AREA)
• Basic Packing Technique (AREA)
• Fluid-Damping Devices (AREA)
• Seal Device For Vehicle (AREA)

Priority Applications (9)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10819273

Family Applications (1)

Country Status (13)

Cited By (10)

Families Citing this family (11)

Citations (5)

Family Cites Families (4)

• 1997
  • 1997-09-19 GB GBGB9719864.2A patent/GB9719864D0/en not_active Ceased
• 1998
  • 1998-09-18 ES ES98946552T patent/ES2219907T3/es not_active Expired - Lifetime
  • 1998-09-18 NZ NZ503445A patent/NZ503445A/xx not_active IP Right Cessation
  • 1998-09-18 AU AU93558/98A patent/AU753123B2/en not_active Expired
  • 1998-09-18 WO PCT/GB1998/002767 patent/WO1999015732A1/en not_active Ceased
  • 1998-09-18 AT AT98946552T patent/ATE264430T1/de active
  • 1998-09-18 DE DE69823212T patent/DE69823212T2/de not_active Expired - Lifetime
  • 1998-09-18 EP EP98946552A patent/EP1015698B1/en not_active Expired - Lifetime
  • 1998-09-18 JP JP2000513015A patent/JP2001517744A/ja active Pending
  • 1998-09-18 US US09/508,101 patent/US6390382B1/en not_active Expired - Lifetime
  • 1998-09-18 PT PT98946552T patent/PT1015698E/pt unknown
  • 1998-09-18 DK DK98946552T patent/DK1015698T3/da active
  • 1998-09-18 CA CA002303836A patent/CA2303836C/en not_active Expired - Fee Related

Patent Citations (5)

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