EP2415933B1

EP2415933B1 - Noise insulation device for rail

Info

Publication number: EP2415933B1
Application number: EP10758579.6A
Authority: EP
Inventors: Yoshifumi Matsuda; Takashi Oguchi; Hiroyuki Abe
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2009-04-03
Filing date: 2010-03-26
Publication date: 2017-10-25
Anticipated expiration: 2030-03-26
Also published as: JP2010242337A; EP2415933A4; EP2415933A1; JP5185877B2; CN102187035B; WO2010113807A1; CN102187035A

Description

Technical Field

The present invention relates to a soundproof device for rails configured to prevent noise generated from railroad rails.

Background Art

As one of soundproof devices of this type, the one described in JP-A-2007-224700 is known, for example. This soundproof device has a configuration as shown in Fig. 11 including three first to third rail ties S (only the second rail tie is illustrated) configured to fix a rail R arranged in sequence from one end to the other end of the rail in the longitudinal direction, a first soundproof cover 81 bridged between the first and second rail ties S, and a second soundproof cover 82 bridged between the second and third rail ties S, in which the length of the first soundproof cover 81 matches a pitch between the first and second rail ties, the length of the second soundproof cover 82 matches a pitch between the second and third rail ties, and required portions of a rail surface are covered with the first soundproof cover 81 and the second soundproof cover 82 in a state of forming a abutting portion 83 between opposed end surfaces of the first soundproof cover 81 and the second soundproof cover 82 on the second rail tie 2.
In this soundproof device, since the pitches of the rail ties vary, preparation of a number of soundproof covers 81, 82 having different lengths are required corresponding to the variations.
In order to avoid this complication, preparation of a single type of the soundproof covers 81, 82 formed into a fixed length so as to match a small tie pitch is also put into practice. In this case, as shown in Fig. 12, the opposed end surfaces of the first soundproof cover 81 and the second soundproof cover 82 may not come into abutment with each other on the second rail tie S and hence a clearance 84 may be formed between the end surfaces (as illustrated in JP-A-2007-120018 ). In this event, noise leaks from the clearance 84, and the soundproof effect is impaired.

Cited Reference

Patent Document

Patent Document 1: JP-A-2007-224700
Patent Document 2: JP-A-2007-120018

Summary of Invention

Problems to be Solved by the Invention

It is an object of the present invention to provide a soundproof device for rails, which does not require preparation of a number of soundproof covers having different lengths, and achieves effective prevention of the noise using a single type of soundproof covers having the same length.

Means for Solving the Problems

A soundproof device for rails according to the present invention includes: three first to third rail ties configured to fix a rail arranged in sequence from one end to the other end of the rail in the longitudinal direction, a first soundproof cover bridged between the first and second rail ties, and a second soundproof cover bridged between the second and third rail ties, and the respective soundproof covers have a fixed length which is longer than any of a pitch of the first and second rail ties and a pitch of the second and third rail ties, and required portions of a rail surface are covered with the first soundproof cover and the second soundproof cover in a state in which opposed end portions of the first soundproof cover and the second soundproof cover are overlapped with each other over a required width on the second rail tie.
According to the soundproof device for rails in the present invention, since a single type of soundproof covers having a larger length than a rail tie pitch are used and the opposed end portions of the adjacent two soundproof covers are overlapped with each other by an extent corresponding to the difference in length, the required portions of the rail surface can be covered entirely without forming a clearance between the opposed end surfaces of the adjacent two soundproof covers.
In addition, when the rail includes a top portion, a waist portion, and a bottom portion continuing from top to bottom in sequence, the soundproof covers each include a cover body bridged from an upper end of a side surface of the waist portion to an extremity of an upper surface of the bottom portion, and a sound absorbing material bonded on an inner surface of the cover body, and a portion of the sound absorbing materials of the respective soundproof covers are removed so that only the cover bodies of the respective soundproof covers are overlapped with each other at a portion where the first soundproof cover and the second sound proof cover are overlapped with each other, the cover bodies only having relatively small thickness can be overlapped with each other with high degree of workability without being interfered by the sound absorbing material having a relatively large thickness at the overlapped portion of the soundproof cover.
It is preferable that the sound absorbing material is obtained by causing the resin to foam. As the resin, polyethylene resin, EPDM, polypropylene resin, and polyvinyl chloride resin are exemplified.
Specifically, if a resin having a cell diameter of 1 mm or smaller and formed of foamed polyethylene member is used from among the resins listed above, a noise reduction effect in a range from 500 to 3.15 kHz which affects the noise level much when the train passes therethrough is achieved significantly.
As specifications of the foamed member, a foaming magnification of 10 to 40, specifically a foaming magnification of 15 to 30 are preferable in view of soundproof property and workability. In addition, a continuous cell ratio of 90% or higher, and a compression stress (25%) of 3 to 5 kPa are preferable.
Also, if the rail includes the head portion, the waist portion, and the bottom portion continued from top to bottom in sequence, the soundproof covers each include a side cover covering the side surface of the waist portion and the upper surface of the bottom portion, and a bottom cover covering the bottom surface of the rail so as to continue from a lower end of the side cover, a large surface area from the side surface of the waist portion of the rail to a lower surface of the bottom portion is covered with the soundproof cover, further soundproof effect can be expected.

Advantages of the Invention

According to the present invention, there is provided a soundproof device for rails, which does not require preparation of a number of soundproof covers having different lengths, and achieves effective prevention of the noise using a single type of soundproof covers having the same length.

Brief Description of the Drawings

Fig. 1 is a vertical longitudinal cross-sectional view of a soundproof device according to the present invention.
Fig. 2 is a side view of the same device.
Fig. 3 is a vertical longitudinal cross-sectional view of the soundproof device according to another embodiment of the present invention.
Fig. 4 is a side view of the same device.
Fig. 5 is a graph of a total frequency showing a soundproof effect brought about by the same device.
Fig. 6 is a graph of respective frequencies of the same device.
Fig. 7 is a table showing test conditions for confirming the soundproof effect depending on the difference of sound absorbing materials used in the same soundproof device.
Fig. 8 is a graph showing a noise reduction effect obtained in a laboratory conducted under the same test conditions.
Fig. 9 is a graph showing results of noise measurement when a train is actually passed therethrough conducted under the same test conditions.
Fig. 10 is a graph showing a result of simulation of the noise reduction effect on the basis of data shown in Fig. 8 and Fig. 9.
Fig. 11 is a side view corresponding to Fig. 2 showing an example in the related art.
Fig. 12 is a side view corresponding to Fig. 2 showing another example in the related art.

Modes for Carrying Out the Invention

Referring now to Fig. 1, a rail R includes a top portion Rt, a waist portion Rw, and a bottom portion Rb continuing from top to bottom in sequence.
Portions from both left and right surfaces of the waist portion Rw to a top surface of the bottom portion Rb are covered with a pair of left and right soundproof covers 11. The both soundproof covers 11 have the same structure although being mirror reversed.
The respective soundproof covers 11 each include a cover body 11A formed of a steel plate bridged from the upper end of a side surface of the waist portion Rw to an extremity of an upper surface of the bottom portion Rb, a thin damping resin damping material 21 and a thick formed resin sound absorbing material 22 bonded on an inner surface of the cover body 11A.
Fig. 2 shows a state of installation of the soundproof cover 11. Three first to third rail ties S1 to S3 are laid down in sequence from the left side to the right side, and the rail R extending in the lateral direction is supported thereby. The rail R is fixed onto the respective first to third rail ties S1 to S3 with tightening members T.
A first soundproof cover 31 is bridged between the first and second rail ties S1, S2, and a second soundproof cover 32 is bridged between the second and third rail ties S2, S3.
A first pitch P1 between the first and second rail ties S1, S2 and a second pitch P2 between the second and third rail ties S2, S3 are the same or the latter is larger than the former. The length L of the first soundproof cover 31 and the second soundproof cover 32 is the same. These sizes have a relationship; P1 ≤ P2 < L.
An overlapped portion 33 is formed at a right end portion of the first soundproof cover 31 and a left end portion of the second soundproof cover 32 on the second rail tie S2, where both are overlapped with each other over a required width B. The width B of the overlapped portion 33 is on the order of 20 to 80 mm, according to the invention and, preferably, 50 mm considering variations in tie pitch and soundproof performance. If it is smaller than 20 mm, when the tie pitch varies significantly, the width of variations become larger than the overlapped portion 33, so that a clearance may be formed and a sound absorbing effect is lowered. If it exceeds 80 mm, the overlapped portion 33 is large, and hence a large amount of the sound absorbing material 22 must be removed, whereby the sound absorbing effect is lowered.
Furthermore, although detail illustration is not given, the damping materials 21 and the sound absorbing materials 22 of the respective soundproof covers 31, 32 are removed so that only the cover bodies (not shown) of the respective soundproof covers 31, 32 are overlapped at the overlapped portion 33 of the right end portion of the first soundproof cover 31 and the second soundproof cover 32.
At the right end portion of the first soundproof cover 31 and the left end portion of the second soundproof cover 32 are formed notches 31a, 32a, respectively, for avoiding interference with the tightening member T.
Fig. 3 shows a modification of a soundproof cover 41. The soundproof cover 41 in this modification includes side covers 42 and a bottom cover 43 formed integrally as a whole.
The side covers 42 have basically the same structure as the soundproof covers 41 shown in Fig. 1, and each include a side cover body 42A formed of a steel plate bridged from the upper end of the side surface of the waist portion Rw to the extremity of the upper surface of the bottom portion Rb, and a damping resin damping material 51 and a foamed resin sound absorbing material 52 bonded on the inner surface of the side cover body 42A. The bottom cover 43 includes a bottom cover body 43A formed of a steel plate aligned at an upper end thereof with a lower end of the side cover body 42A and having a L-shape in lateral cross section, and a damping resin damping material 53 and a foamed resin sound absorbing material 54 bonded on an upper surface of a horizontal portion thereof.
The soundproof covers 41 in this modification includes an overlapped portion 61 formed on a single rail tie S by opposed end portions of the two adjacent soundproof covers 41 as shown in Fig 4. The side cover 42 is formed with notches 71, 72 in the same manner as the notches 31a, 32a shown in Fig. 2. The bottom cover 43 is formed with notches 73, 74 for avoiding interference with the rail tie S.
The result of measurement of the soundproof effect of the soundproof cover according to the application of the present invention will be described in comparison with the soundproof effect brought about by the soundproof cover described in the section of Background Art.
The method of measurement will be as follows. The 50N rail R with a tie span of 600 mm is oscillated by pink noise fed from an oscillation speaker. In order to prevent the effect of a direct sound from the oscillation speaker, a microphone is placed at a position of 100 mm from the waist portion Rw of the rail R at a position of 2 m apart from a shaking point, and then the noise level is measured.
The soundproof effect is calculated by subtracting a sound pressure level of the rail R provided with the cover from a sound pressure level of the naked rail R, which is the rail R not provided with the cover.
Fig. 5 and Fig. 6 show the results of the measurement. Fig. 5 shows total average values of the sound pressure in a range from 400 to 4kHz, and Fig. 6 shows sound pressures at frequencies in a range from 400 to 4kHz, respectively.
In Fig. 5 and Fig. 6, a sign a represents a case where there is no clearance between the covers as shown in Fig. 7, a sign b represents a case where there is a clearance between the covers as shown in Fig. 8, a sign c represents a case where end portions of the covers are overlapped with each other as shown in Fig. 1, and a sign d represents a case where a bottom surface of the rail R is covered with the cover as shown in Fig. 3 in addition to the covered surface shown by the sign c, respectively.
As shown by the sign b, when there is the clearance between the covers, the sound pressure reduction effect is the lowest. In the case where there is no clearance between the covers as shown by the sign a and the case where the end portions of the covers are overlapped with each other as shown by the sign c, the sound pressure reduction effect is achieved by the same extent. In addition, the fact that the sound pressure reduction effect is higher when the bottom surface of the rail R is covered with the cover is as shown by the sign d.
The cover body described above is not limited to be formed of the steel plate, but may be formed of resin. However, when the covers are abutted without clearance therebetween as shown by the sign a as described above, there is a probability of formation of the clearance due to the thermal contraction of the rail. In this case, the sound pressure reduction effect may be lowered.
The fact that the soundproof effect is improved by forming the sound absorbing material of foamed resin member is proved by a test described below.
Fig. 7 shows test conditions. Measured data of the sound reduction effect in a laboratory using the resins under the conditions shown in Fig. 7 is shown in Fig. 8. Fig. 9 shows sound measurement data measured when a train is actually passed therethrough using the resins under the same conditions. Fig. 10 shows a result of simulation of the sound pressure reduction effects of the above-described various resins from the sound pressure levels when the train is passed therethrough using the data shown in Fig. 8 and Fig. 9. In any of Fig. 8 to Fig. 10, it is understood that the soundproof performance of the sound absorbing material, polyethylene resin having a cell diameter of 0.5 to 1 mm and a foaming magnification of 30 is superior.
When executing the soundproof covers on the spot, notches as a runout for the tightening member may be formed by on-the-spot adjustment on the spot of execution or may be formed in advance. With the on-the-spot adjustment, execution of the soundproof covers may be performed for the rails without being affected by a change of the tie pitch. In addition, the soundproof covers can be prepared without being bound by the notches. Therefore, the soundproof covers having a length longer than the tie pitch can easily be used, and hence the workability is improved.
In addition, when the sound proof covers carried into the spot of execution are rolled, the handling of the rolled soundproof cover is facilitated.
Although the illustration is omitted, urethane foamed material or the like may be injected into clearances between the overlapped portion 33 of the soundproof covers and the rail R (positions where the sound absorbing materials 22 are omitted), whereby the sound absorbing effect can be enhanced by filling the clearances.

Industrial Applicability

The soundproof device for rails according to the present invention does not require preparation of a number of soundproof covers having different lengths, and achieve the effective prevention of the noise using a single type of soundproof covers having the same length.

Reference Numerals

S1 to S3:: rail tie
31:: first soundproof cover
32:: second soundproof cover
L:: cover length
P1, P2:: tie pitch
R:: rail

Claims

A soundproof device for rails comprising: three first to third rail ties (S1, S2, S3) configured to fix a rail (R) arranged in sequence from one end to the other end of the rail in the longitudinal direction, a first soundproof cover (31) bridged between the first and second rail ties (S1, S2), and a second soundproof cover (32) bridged between the second and third rail ties (S2, S3), wherein the respective soundproof covers have a fixed length which is longer than any of a pitch (P) of the first and second rail ties and a pitch of the second and third rail ties, and portions of a rail surface are covered with the first soundproof cover (31) and the second soundproof cover (32) in a state in which opposed end portions of the first soundproof cover and the second soundproof cover are overlapped with each other forming an overlapped portion (33) over a width of 20 to 80 mm on the second rail tie,
further comprising a sound absorbing material (22) bonded on an inner surface of each cover body,
and wherein a first pitch (P1) between the first and second rail ties (S1, S2) and a second pitch (P2) between the second and third rail ties (S2, S3) are the same or the latter is larger than the former, and the length L of the first soundproof cover and the second soundproof cover is the same, and the sizes have a relationship; P1 ≤ P2 < L.
The soundproof device for rails according to Claim 1, wherein the rail includes a top portion, a waist portion, and a bottom portion continuing from top to bottom in sequence, soundproof covers (11) each include a cover body (11A) bridged from an upper end of a side surface of the waist portion to an extremity of an upper surface of the bottom portion, and the cover bodies (11A) of the respective soundproof covers (11) are overlapped with each other at a portion where the first soundproof cover and the second sound proof cover are overlapped with each other.
The soundproof device for rails according to Claim 1, wherein the sound absorbing material (22) is a resin formed of polyethylene and the cell diameter thereof is 3 mm or smaller.
The soundproof device for rails according to Claim 1, wherein the rail includes a head portion (Rt), a waist portion (Rw), and a bottom portion (Rb) continuing from top to bottom in sequence, the soundproof covers each include a side cover (42) covering the side surface of the waist portion and the upper surface of the bottom portion, and a bottom cover (43) covering the bottom surface of the rail so as to continue from a lower end of the side cover, wherein the side covers (42) each include a side cover body (42A) formed of a steel plate bridged from the upper end of the side surface of the waist portion (Rw) to the extremity of the upper surface of the bottom portion (Rb), and a damping resin damping material (51) and a foamed resin sound absorbing material (52) bonded on the inner surface of the side cover body (42A), and wherein the bottom cover (43) includes a bottom cover body (43A) formed of a steel plate aligned at an upper end thereof with a lower end of the side cover body (42A) and having a L-shape in lateral cross section, and a damping resin damping material (53) and a foamed resin sound absorbing material (54) bonded on an upper surface of a horizontal portion thereof..
The soundproof device for rails according to Claim 4, wherein the sound absorbing material (54) is a resin formed of polyethylene and the cell diameter thereof is 3 mm or smaller.
The soundproof device for rails according to any one of Claims 4 and 5, wherein the soundproof covers include an overlapped portion (61) formed on a single rail tie (S) by opposed end portions of the two adjacent soundproof covers (41), and the side cover (42) is formed with notches (71, 72), and the bottom cover (43) is formed with notches (73, 74).