SOUNDPROOF WHEEL FOR RAILWAY VEHICLE
TECHNICAL FIELD
[0001]
The present invention relates to a soundproof wheel for a railway vehicle.
BACKGROUND ART
[0002]
The noise generated when a railway vehicle travels is a top-priority issue to be
solved for railroad wayside environments. Such noise includes those generated
from wheels. Noise generated from a wheel includes wheel rolling noise and socalled
squeak noise. The squeak noise is mostly generated when a vehicle passes a
curved road having a large curvature. The wheel rolling noise is generated not only
when a vehicle passes a curved road but also when it passes a straight road.
[0003]
The surface of a rail, as well as the surface of a wheel (tread) which comes
into contact therewith have minute unevenness. As a result, when the wheel rolls
on the rail, the wheel and the rail are excited, conceivably causing wheel rolling
noise. It is also conceived that the squeak noise is attributable to the vibration of
the wheel. There is a case in which a portion in the rail, which comes into contact
with a tread of the wheel, has wave-like wear (hereafter, referred to as "wavy wear").
As a peculiar wheel noise, when the vehicle passes on a rail which has such wavy
wear, the wheel is severely excited, thus causing noise.
[0004]
To reduce the noise generated by the vibration of a wheel (hereafter, referred
to as "wheel vibration noise"), Patent Literatures 1 and 2 have proposed a soundproof
wheel in which a soundproofing device is attached to an inner peripheral side of a
rim section of the wheel. Such a soundproof wheel is equipped with a
soundproofing device which is composed of a combination of an elastic body section
2
such as rubber and an additional mass section and a soundproofing device is attached
to an attachment groove formed in an inner periphe_ral surface.of.t~~ ri111 se._~tion with
a metal attachment.
[0005]
Such a soundproofing device is considered to act as a dynamic vibration
absorber. A dynamic vibration absorber has a resonance frequency, which
coincides with a natural frequency of a structure, and can absorb (reduce) the
vibration of the structure through resonance. Therefore, by attaching such a
soundproofing device to a wheel, it is possible to reduce the noise due to natural
vibration of the coinciding frequency. The resonance frequency f of a
soundproofing device is given by:
f= (1/2n) x (klm)112 ... (1)
where n is the circular constant, k is a spring constant of the elastic body section, and
m is the mass of the additional mass section. Therefore, given a natural frequency
of a wheel, it is possible to determine the spring constant k and the mass m of the
additional mass section from Formula ( 1) such that the resonance frequency f of the
soundproofing device coincides with the natural frequency.
[0006]
A wheel normally has multiple natural vibration modes, and natural
frequencies corresponding to each of those natural vibration modes. Therefore, a
wheel has multiple natural frequencies. Patent Literatures 2 and 3 have proposed a
soundproof wheel including a plurality of soundproofing devices each having a
different resonance frequency, in which the resonance frequency of each sound
proofing device coincides with any ofthe multiple natural frequencies of the wheel.
According to these soundproof wheels, it is possible to concurrently reduce noise
corresponding to multiple natural frequencies.
[0007]
Specifically, in the wheel of Patent Literature 2, two soundproofing devices
are used in which two types of elastic bodies each having a different elastic constant
are used respectively, such that the resonance frequencies of the two soundproofing
devices are different from each other. In the wheel of Patent Literature 3, a
soundproofing device (a dynamic vibration absorber consisting of an elastic body
3
and an abutment plate) is divided in a circumferential direction of the soundproof
wheel, and an adjustment is made such that each res-onance fre._quency ofthe divided - - --- -· ---- ·-
soundproofing devices coincides with any of natural frequencies ofthe wheel. Such
a configuration makes it possible to concurrently absorb noise components
corresponding to two or more levels of frequencies. Further, as a result of being
divided in the circumferential direction ofthe soundproof wheel, the soundproofing
device disclosed in Patent Literature 3 makes it possible to increase the natural
frequencies of the abutment plate to higher frequencies which will not cause any
problem as noise.
[0008]
Among natural vibration modes of a wheel, a primary mode which may cause
wheel rolling noise is one in which the rim section vibrates in an in-plane direction
and the plate section vibrates in an out-of-plane direction. Such noise due to natural
vibrations include at least, 3 levels of frequency components, for example, around 2
kHz, around 3 kHz, and around 4 kHz in a range of I kHz to 10 kHz of frequency
ranges to which human auditory sense is sensitive.
[0009]
Meanwhile, when a vehicle is traveling at a high speed, the soundproofing
device is subject to various forces, causing a risk that the soundproofing device falls
off from the wheel. In the inventions according to Patent Literatures 1 to 3,
sufficient measures have not been taken to prevent the soundproofing device from
falling off from the wheel.
[0010]
Patent Literature 4 discloses a soundproofing device including a ring-shape
additional mass section, and an elastic body section attached to an outer peripheral
portion of the additional mass section. In this soundproofing device, the elastic
body section is disposed within a groove formed in a rim section.
[00 II]
The soundproof wheel of Patent Literature 4 is configured such that the elastic
body section is fixed to a bottom portion of a groove formed in the rim section and to
the additional mass section, while the additional mass section is movable with
4
respect to the rim section. Such configuration allows absorption of vibration of the
wheel.
[0012]
In this soundproofing device, since the opening side of the groove is blocked
by the additional mass section with respect to the elastic body section, the elastic
body section is not likely to fall off from the wheel even if it is separated from the
additional mass section. However, in this invention, when the elastic body section
deteriorates, the displacement of the additional mass section with respect to the rim
section during travelling of the vehicle increases, and the additional mass section
may collide with other members, such as a brake disk. Moreover, as a result of that
the inner surface of the groove of the rim section and the additional mass section are
rubbed against each other, a flaw may occur in the rim section and the additional
mass section, or these members may be worn. Further, when the elastic body
section is separated completely, there is possibility that additional mass section falls
off from the wheel. For this reason, a wheel equipped with the soundproofing
device is less durable.
CITATION LIST
PATENT LITERATURE
[0013]
Patent Literature 1: Japanese Utility Model No. 2577323
Patent Literature 2: Japanese Patent No. 3097831
Patent Literature 3: Japanese Patent Application Publication No. 58-116202
Patent Literature 4: Japanese Patent Application Publication No. 2006-182136
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0014]
Accordingly, it is an objective ofthe present invention to provide a
soundproof wheel for a railway vehicle, which allows for significant reduction in
noise caused by the vibration of the wheel, and is also excellent in durability.
5
SOLUTION TO PROBLEM
[0015]
The soundproof wheel of the present invention is a soundproof wheel for a
railway vehicle with a soundproofing device mounted onto an inner peripheral
surface of a rim section of the wheel. The soundproofing device includes a fixing
ring, a first elastic body section, an additional mass section, and a second elastic
body section. The fixing ring is fixed to the rim section with at least an outer
peripheral portion of the fixing ring fitted in a groove formed along a circumferential
direction in the inner peripheral surface of the rim section. The first elastic body
section is stuck to an outer peripheral surface of the fixing ring, and is disposed
within the groove. The additional mass section is stuck to a side of the first elastic
body section opposite to the fixing ring, and is disposed within the groove. The
second elastic body section is stuck to a side of the additional mass section opposite
to the first elastic body section, and is provided in the groove in such a way that no
gap is formed between the second elastic body section and a bottom of the groove.
The first elastic body section includes a plurality of first elastic body pieces which
are spaced apart from each other in a circumferential direction of the fixing ring.
The second elastic body section includes a plurality of second elastic body pieces
which are spaced apart from each other in the circumferential direction of the fixing
ring. The additional mass section includes a plurality of additional mass pieces
which are spaced apart from each other in the circumferential direction of the fixing
ring. Each additional mass piece is stuck to any of the plurality of first elastic body
pieces, and any of the plurality of second elastic body pieces. The wheel has
multiple natural frequencies corresponding to multiple natural vibration modes.
The soundproofing device includes a plurality of dynamic vibration absorbers.
Each dynamic vibration absorber has the additional mass piece, and the first and
second elastic body pieces which are stuck to the concerned additional mass piece.
At least one dynamic vibration absorber of the plurality of dynamic vibration
absorbers has a resonance frequency different from the resonance frequency of
another dynamic vibration absorber. Any of the resonance frequencies ofthe
plurality of dynamic vibration absorbers corresponds to any of the multiple natural
frequencies.
6
[00 16]
A spacer member may be provided between ~he second_ elas~ic body __ st::ction
and the bottom of the groove.
The soundproof wheel preferably includes a protrusion interposed between
the dynamic vibration absorbers adjacent to each other, and protruding from the outer
peripheral surface of the fixing ring. When the soundproof wheel includes the
protrusion, a distal end of the protrusion may be in contact with the bottom of the
groove.
ADVANTAGEOUS EFFECTS OF INVENTION
[0017]
According to the present invention, the vibration of a wheel is transmitted
from the rim section to the plurality of dynamic vibration absorbers (the first and
second elastic body pieces, and additional mass pieces) through the fixing ring.
Since at least one dynamic vibration absorber of the plurality of dynamic vibration
absorbers has a resonance frequency different from the resonance frequency of
another dynamic vibration absorber, the resonance frequency of each dynamic
vibration absorber corresponds to any of the multiple natural frequencies of the
wheel, it is possible to concurrently reduce noise corresponding to natural
frequencies of not less than 2 levels, thereby significantly reducing wheel vibration
noise. Each dynamic vibration absorber includes first and second elastic body
pieces, and spring constants of the first and second elastic body pieces can be
selected independently. Therefore, a large degree offreedom is given for
adjustment of the resonance frequency of each dynamic vibration absorber.
[0018]
Moreover, according to the present invention, the first and second elastic body
sections and the additional mass section are disposed within a groove of the rim
section, and a fixing ring fixed to the rim section is present on an opening side of the
groove with respect to the first and second elastic body sections and the additional
mass section. For this reason, even if the additional mass section is separated from
the first and second elastic body sections, or the first and second elastic body sections
are respectively separated from the fixing ring and the bottom of the groove, it is less
7
likely that thus separated first and second elastic body sections, and the additional
mass section fall off the wheel.
[0019]
Further, due to the configuration that the fixing ring which is one of the
components constituting the soundproofing device is fixed to the rim section of the
wheel, there will be no rubbing between the soundproofing device and the rim
section of the wheel. Furthermore, even if the elastic body section deteriorates,
resulting in decline in elasticity thereof, the additional mass section will not collide
with any member outside the groove. Therefore, the soundproof wheel is highly
durable.
BRIEF DESCRIPTION OF DRAWINGS
[0020]
[FIG. lA] FIG. lA is a sectional view of a soundproofwheel according to an
embodiment of the present invention, showing one side portion of the soundproof
wheel with respect to its central axis.
[FIG. 1 B] FIG. I B is an enlarged view of a region shown by a circle C in FIG.
IA.
[FIG. 2] FIG. 2 is a plan view to show an example of a soundproofing device
which can be used for a soundproof wheel of the present invention.
[FIG. 3] FIG. 3 is a sectional view to show a surrounding portion of a groove
of a soundproof wheel according to a first variation of the embodiment shown in
FIGS. IA and lB.
[FIG. 4] FIG. 4 is a plan view to show another example of the soundproofing
device which can be used for the soundproof wheel of the present invention.
[FIG. 5] FIG. 5 is·a sectional view to show the surrounding of a groove of a
soundproof wheel according to a second variation of the embodiment shown in FIG.
IA to FIG. 2.
[FIG. 6] FIG. 6 is a sectional view of a soundproof wheel according to a third
variation of the embodiment shown in FIG. lA to FIG. 2.
[FIG. 7A] FIG. 7A is a sectional view of a soundproofwheel according to a
fourth variation of the embodiment shown in FIG. lA to FIG. 2.
8
[FIG. 7B] FIG. 7B is a sectional view of a soundproof wheel according to a
fifth variation ofthe embodiment shown in FIG. 1~ to FIG. 2,_
[FIG. 8] FIG. 8 is a schematic diagram to show a configuration of a wheel
rolling noise tester.
[FIG. 9] FIG. 9 is a diagram to show noise correction levels to be used when
performing noise analysis.
[FIG. 1 0] FIG. 10 is a diagram showing a relationship between a 1/3 octave
band center frequency and a noise level for Examples 1 to 4 and Comparative
Example 1.
[FIG. 11] FIG. 11 is a diagram showing a relationship between a 1/3 octave
band center frequency and a noise level for Comparative Examples 1 to 5.
[FIG. 12] FIG. 12 is a diagram showing a relationship between a
circumferential speed of the rail wheel and a noise level for Examples 1 to 4, and
Comparative Example 1.
[FIG. 13] FIG. 13 is a diagram showing a relationship between a
circumferential speed of rail wheel and a noise level for Comparative Examples 1 to
5.
DESCRIPTION OF EMBODIMENTS
[0021]
Hereafter, embodiments of the present invention will be described in detail
with reference to the appended drawings.
FIGS. 1A and 1B are sectional views of a soundproofwheel according to an
embodiment ofthe present invention. FIG. 1A is a view showing one side portion
of the soundproof wheel with respect to its central axis, and FIG. 1B is an enlarged
view of a region shown by a circle C in FIG. lA.
[0022]
The soundproof wheel 1, which is used for railway vehicles, includes a wheel
2 and a soundproofing device 3. The wheel2 includes an annular plate section 4,
and an annular rim section 5 located in an outer peripheral portion of the plate
section 4. The rim section 5 protrudes to both sides in the thickness direction of the
plate section 4 with respect to the plate section 4, and has an inner peripheral surface
9
6 which faces a central axis A of the soundproof whee! I. In an outer peripheral
surface of the rim section 5, a flange 7 protrudes, at_ one side with r~spe9t t~the
direction along the central axis A, in the opposite direction to the central axis A.
[0023]
In the rim section 5, a groove 8, which opens up in a direction toward the
central axis A, is formed in an annular shape around the central axis A in the inner
peripheral surface 6 on one side (the same side of the flange 7) with respect to the
direction along the central axis A. The soundproofing device 3 is fitted in the
groove 8 over the entire circumference of the groove 8.
[0024]
The soundproofing device 3 includes a fixing ring 10, a first elastic body
section llA, an additional mass section 12, and a second elastic body section liB.
The first elastic body section 11 A is stuck to an outer peripheral surface 1 Oa of the
fixing ring 10. The additional mass section 12 is stuck to a side ofthe first elastic
body section 11 A opposite to the fixing ring 10. The second elastic body section
11 B is stuck to a side of the additional mass section 12 opposite to the first elastic
body section 11 A. The fixing ring 10 is made of a high rigidity material such as a
metal including steel. The fixing ring 10 has an outer peripheral side portion in the
radial direction to be fitted in the groove 8 and fixed to the rim section 5. The
fixing of the fixing ring 1 0 to the rim section 5 can be performed by, for example,
welding, caulking, bonding, etc.
[0025]
A width (length in an axial direction of the soundproofing device 3) of the
fixing ring 1 0 is about the same as a width of the groove 8, and the opening part of
the groove 8 is sealed by the fixing ring 10. The first elastic body section 11 A, the
additional mass section 12, and the second elastic body section 11 B are disposed
within this sealed space in the groove 8. Widths ofthe first and second elastic body
sections 11 A, 11 B and the additional mass section 12 are narrower than the width of
the fixing ring 10, and the first and second elastic body sections 11 A, 11 B and the
additional mass section 12 are spaced apart from the inner wall of the groove 8.
The second elastic body liB is in contact with the bottom ofthe groove 8.
[0026]
10
The first elastic body section 11 A and the second elastic body section 11 B
may be made ofthe same kind of material, or kinds_ofmaterials_ wpjch are _ ~ifferent
from each other. The first and second elastic body sections llA, liB may be made
of, for example, rubber. The vibration generated in the wheel2 while a vehicle is
travelling is transmitted to the first and second elastic body sections llA, liB, and
the additional mass section 12 through the fixing ring 10 and the rim section 5,
thereby causing the first and second elastic body sections 11 A, 11 B and the
additional mass section 12 to vibrate.
[0027]
The first and second elastic body sections 11 A, 11 B and the additional mass
section 12 are disposed within the groove 8 ofthe rim section 5. Moreover, the
fixing ring 1 0 fixed to the rim section 8 is present on an opening side of the groove 8
with respect to the first and second elastic body sections 11A, 11B and the additional
mass section 12. For that reason, even if the first elastic body section 11 A is
separated from the fixing ring 1 0 or the additional mass section 12, and the second
elastic body section liB is separated from the bottom of the groove 8 or the
additional mass section 12, the additional mass section 12 is not likely to fall offthe
soundproof wheel 1.
[0028]
Due to the configuration that the fixing ring 1 0 which is one of the
components constituting the soundproofing device 3 is fixed to the rim section 5 of
the wheel 2, there will be no rubbing between the soundproofing device 3 and the
rim section 5 of the wheel 2. Moreover, due to the configuration that the additional
mass section 12 is present in the groove 8 which is sealed by the fixing ring 1 0, even
if the first and second elastic body sections llA, 11B deteriorate, resulting in decline
in elasticity thereof, the additional mass section 12 will not collide with any member
(for example, a brake disc) outside the groove 8. Therefore, the soundproof wheel 1
is highly durable.
[0029]
FIG. 2 is a plan view to show an example of the soundproofing device 3.
The first elastic body section 11 A includes a plurality of first elastic body
pieces 13A spaced apart from each other in a circumferential direction ofthe
11
soundproofing device 3. The additional mass section 12 includes a plurality of
additional mass pieces 14 spaced apart from each o!her in the ~i_rcu_1pferentj_al
direction ofthe soundproofing device 3. The second elastic body section liB
includes a plurality of second elastic body pieces 13B which are spaced apart from
each other in the circumferential direction of the soundproofing device 3. In the
example of FIG. 2, the first and second elastic body sections llA and liB include 12
first and second elastic body pieces 13A and 13B respectively, and the additional
mass section 12 includes 12 additional mass pieces 14. Each additional mass piece
14 is stuck to any of the first elastic body pieces 13A and any of the second elastic
body pieces 13B.
[0030]
The second elastic body piece 13B may be stuck to the bottom ofthe groove 8.
Also, the second elastic body piece 13B may not be stuck to the bottom of the groove
8 and in this case, it is necessary that the second elastic body piece 13B is
sufficiently pressed by the additional mass piece 14 and the bottom of the groove 8.
In either case, the soundproof wheel having the soundproofing device 3 is configured
such that even if the additional mass piece 14 vibrates during travelling of a railway
vehicle equipped with this soundproof wheel, a gap between the second elastic body
piece 13B and the bottom ofthe groove 8 will not be generated.
[0031]
Each additional mass piece 14 and the first and second elastic body pieces
13A, 13B stuck to the concerned additional mass piece 14 constitute a dynamic
vibration absorber 15. In the example ofFIG. 2, the soundproofing device 3
includes 12 dynamic vibration absorbers 15A to 15L. Regarding the
circumferential direction of the soundproofing device 3, the additional mass piece 14
and the first and second elastic body pieces 13A, 13B, which constitute each
dynamic vibration absorber 15, have a substantially flush end face.
[0032]
The wheel 2 normally has multiple natural frequencies respectively
corresponding to multiple natural vibration modes. At least one dynamic vibration
absorber 15 of the dynamic vibration absorbers 15A to 15L has a resonance
frequency different from that of another dynamic vibration absorber 15. That is, the
12
dynamic vibration absorbers 15A to 15L have at least two resonance frequencies.
Any of the resonance frequencies of the dynamic vLbration absorbe_rs 15A !91 5L
coincides with any of the natural frequencies of the wheel2. As a result, it is
possible to concurrently reduce noise corresponding to at least two natural
frequencies, among the multiple natural frequencies of the wheel 2.
[0033]
The dynamic vibration absorbers 15A to 15L preferably have at least three
resonance frequencies, each of which coincides with any natural frequency ofthe
wheel2. This makes it possible to efficiently reduce noise of the wheel2.
[0034]
As described above, wheel rolling noise due to natural vibrations of the plate
section 4 and the rim section 5 is generated from the wheel 2. Such noise includes,
for example, frequency components of2.0 kHz, 2.5 kHz, and 3.0 kHz in frequency
ranges to which human auditory sense is sensitive, for example, a range of 1 kHz to
10kHz.
[0035]
Accordingly, for example, it may be assumed that the dynamic vibration
absorbers 15A to 15L are divided into the following first to third groups. The
dynamic vibration absorbers 15 belonging to the first group each have a resonance
frequency of 2.0 kHz. The dynamic vibration absorbers 15 belonging to the second
group each have a resonance frequency of 2.5 kHz. The dynamic vibration
absorbers 15 belonging to the third group each have a resonance frequency of3.0
kHz. As a result, it is possible to significantly reduce noise in auditory sense. The
first to third groups can be each made up of 4 dynamic vibration absorbers 15.
[0036]
Moreover, configuring any of the dynamic vibration absorbers 15A to 15L to
have a resonance frequency corresponding to a frequency of squeak noise makes it
possible to reduce the squeak noise. Similarly, configuring any of the dynamic
vibration absorbers 15A to 15L to have a resonance frequency corresponding to a
frequency of noise attributable to wavy wear makes it possible to reduce such noise.
[0037]
13
The resonance frequency of each of the dynamic vibration absorbers 15A to
15L can be made to have a desired value by appropriately sele.cting_a spring constant
k1 of the first elastic body piece 13A, a spring constant k2 ofthe second elastic body
piece 13B, and a mass m ofthe additional mass piece 14 based on the following
Formula (2):
f= (l/2n) x ((k1 + k2)/m) 112 ... (2)
[0038]
Due to the configuration that even if the additional mass piece 14 vibrates
during travelling of a railway vehicle equipped with this soundproofing device 3, a
gap between the second elastic body piece 13B and the bottom ofthe groove 8 will
not be generated, the resonance frequency of each dynamic vibration absorber 15A to
15L will be maintained at a value as designed.
[0039]
The soundproof wheel 1 can be produced by first providing the soundproofing
device 3 with a disconnected part in the circumference thereof, and after fitting the
additional mass section 12, the first and second elastic body sections 11 A, 11 B, and
an outer peripheral portion of the fixing ring 10 in the groove 8 of the rim section 5,
joining the disconnected sections of the soundproofing device 3 by, for example,
welding.
[0040]
Regarding the axial direction of the soundproofing device 3, the lengths ofthe
first and second elastic body sections 11 A, 11 B (each first and second elastic body
piece 13A, 13B) are not less than 5 mm and not more than 10 mm, and the length of
the additional mass section 12 (each additional mass piece 14) is not less than 5 mm
and not more than 10 mm. As a result of the first and second elastic body sections
llA, liB, and the additional mass section 12 having such sizes, attachment thereof
to the fixing ring 10, and adjustment of resonance frequencies thereof become easy.
[0041]
FIG. 3 is a sectional view to show a surrounding portion of a groove of a
soundproof wheel according to a first variation of the embodiment shown in FIGS.
IA and 1 B. FIG. 3 shows a section including a central axis of the soundproof
wheel. In FIG. 3, components corresponding to the components shown in FIG. IB
14
are given the same reference symbols as those ofFIG. 18, thus omitting description
thereof.
[0042]
In this variation, a spacer member 16 is provided so as to contact closely with
the bottom of the groove 8 and fill the spacing between the second elastic body
section 118 and the bottom of the groove 8. Therefore, although the second elastic
body section 11 8 is spaced apart from the bottom of the groove 8, there is no gap
(void) between the second elastic body section 11 Band the bottom of the groove 8.
The spacer member 16 is made of a high rigidity material, for example, a metal such
as steel.
[0043]
The spacer member 16 may be a ring-shape member which is continuous over
the entire circumference of the soundproofing device like the fixing ring 10, or may
include multiple members which are spaced apart from each other in the
circumferential direction of the soundproofing device. In either case, as with the
embodiment shown in FIGS. 1A and 18, it is possible to design the dynamic
vibration absorber so as to have a desired resonance frequency according to Formula
(2) described above.
[0044]
FIG. 4 is a plan view to show another example of the soundproofing device
which can be adopted in the soundproof wheel of FIGS. 1A and I8. In FIG. 4,
components corresponding to the components shown in FIG. 2 are given the same
reference symbols as those of FIG. 2, thus omitting description thereof.
[0045]
The soundproofing device 38 includes a ring-shape spacer member 16 which
is continuous over the entire circumference thereof. The spacer member 16 may be
stuck to the second elastic body piece 138. Moreover, the spacer member 16 may
not be stuck to the second elastic body piece 138 and in this case, it is necessary that
the second elastic body piece 138 is sufficiently pressed by the additional mass piece
14 and the spacer member 16. In either case, the soundproofing device 38 is
configured such that even if the additional mass piece 14 vibrates during travelling of
a railway vehicle equipped with the soundproofing device 38, a gap between the
15
second elastic body piece 13B and the spacer member 16 will not be generated.
This allows the resonance frequency of each dynall!_ic vibratiop ab~(_)rber I?_to be
maintained at a value as designed.
[0046]
In the soundproof wheel of the present invention, the number of the dynamic
vibration absorbers 15 will not be limited. For example, 12 dynamic vibration
absorbers 15 may be provided as shown in FIG. 2, or 24 dynamic vibration absorbers
15 may be provided as shown in FIG. 4. In the case ofthe soundproofing device 3B
of FIG. 4, since the number of the dynamic vibration absorbers 15 increases
compared with in the soundproofing device 3 of FIG. 2, it is possible to increase the
number of resonance frequencies of the dynamic vibration absorbers 15 which
correspond to natural vibration of the wheel 2. Further, since even when the first or
second elastic body piece 13A, 13B of some of the dynamic vibration absorbers 15
deteriorates, resulting in deterioration of the performance as the dynamic vibration
absorber 15, vibration can be reduced by other dynamic vibration absorbers 15, it is
possible to suppress deterioration in performance of controlling vibration (reducing
noise caused by vibration) of the wheel 2. It becomes easier to obtain such effect as
the number of the dynamic vibration absorbers 15 increases.
[0047]
On the other hand, increase in the number of the dynamic vibration absorbers
15 will result in decrease in the lengths of the additional mass piece 14 and the first
and second elastic body pieces 13A, 13B in the circumferential direction of the
wheel 2. As a result, the additional mass piece 14 may become more likely to be
separated from the fixing ring 10 (and the spacer member 16) due to deterioration of
the first and second elastic body pieces 13A, 13B. It is possible to make such
separation less likely to occur by decreasing the number of the dynamic vibration
absorbers 15, thereby increasing the lengths in the circumferential direction ofthe
wheel 2 for the additional mass piece 14 and the first and second elastic body pieces
13A, 13B. However, since the additional mass piece 14 remains in the groove 8
sealed by the fixing ring 10 even if it is separated from the fixing ring 10 (and the
spacer member 16), the possibility that it falls off is very low.
[0048]
16
FIG. 5 is a sectional view to show the surrounding of a groove of a
soundproof wheel according to a second variation of the embo,djrn~!lt sl}o~!lin FIG.
1A to FIG. 2. FIG. 5 shows a section perpendicular to the central axis ofthe
soundproof wheel. In FIG. 5, components corresponding to the components shown
in FIGS. 3 and 4 are given the same reference symbols as those of FIGS. 3 and 4,
thus omitting description thereof.
[0049]
In this soundproofing device, the spacer member includes a spacer member
16A and a spacer member 16B, which are spaced apart in the circumferential
direction of the soundproofing device, and have different thicknesses. This
soundproofing device includes a dynamic vibration absorber 15X and a dynamic
vibration absorber 15Y. The dynamic vibration absorber 15X includes a first elastic
body piece 13A 1, an additional mass piece 14, and a second elastic body piece 13B 1.
The dynamic vibration absorber 15Y includes a first elastic body piece 13A2, an
additional mass piece 14, and a second elastic body piece 13B2.
[0050]
The thickness of the additional mass piece 14 ofthe dynamic vibration
absorber 15X is about the same as that of the additional mass piece 14 of the
dynamic vibration absorber 15Y. On the other hand, the first elastic body piece
13A2 of the dynamic vibration absorber 15Y has a thickness larger than that of the
first elastic body piece 13A 1 of the dynamic vibration absorber 15X, and the second
elastic body piece 13B2 ofthe dynamic vibration absorber 15Y has a thickness larger
than that of the second elastic body piece 13B1 ofthe dynamic vibration absorber
15X. Thus, by making the thicknesses of the first and second elastic body pieces
13A 1, 13A2, 13B 1, 13B2 different from each other, thereby making the spring
constant of each of these elastic body pieces,. it is possible to configure the dynamic
vibration absorber 15X and the dynamic vibration absorber 15Y so as to have desired
resonance frequencies which are different from each other.
[0051]
In this case, as shown in FIG. 5, by making the spacer member 16B ofthe
dynamic vibration absorber 15Y be thinner than the spacer member 16A of the
dynamic vibration absorber 15X, it is possible to configure such that the total
17
thickness ofthe first elastic body piece 13Al, the additional mass piece 14, the
second elastic body piece 13Bl, and the spacer melilber 16A s_ubst~ptia]ly ~q_uals to
the total thickness of the first elastic body piece 13A2, the additional mass piece 14,
the second elastic body piece 13B2, and the spacer member 16B. Therefore,
according to this configuration, by adopting spacer members 16A, 16B having
appropriate thicknesses, it is possible to prevent a gap from being generated between
the second elastic body pieces 13 B 1, 13 B2 and the bottom of the groove 8 even
when the total thickness of the first and second elastic body pieces 13A 1, 13B 1 is
different from the total thickness of the first and the second elastic body pieces 13A2,
13B2.
[0052]
FIG. 6 is a sectional view of a soundproof wheel according to a third variation
of the embodiment shown in FIG. IA to FIG. 2. FIG. 6 shows a section including
the central axis of a wheel. In FIG. 6, components corresponding to the
components shown in FIG. IB are given the same reference symbols as those of FIG.
1B, thus omitting description thereof.
[0053]
In this soundproof wheel, a groove 8A which is opened toward the central
axis of the wheel is formed in a rim section 5 of the wheel. A fixing ring 1 0
included in the soundproofing device 3 is fitted in the groove 8A. As a result, a
sealed space is formed in the groove 8A. The first and second elastic body sections
11A and liB and the additional mass section 12 are disposed within the sealed space
in the groove 8A.
[0054]
The fixing ring 1 0 has a substantially constant width with regard to the
circumferential direction and the radial direction ofthe soundproofing device 3.
The groove 8A includes a first portion 8A 1, and a second portion 8A2 which is
formed nearer the bottom of the groove 8A with respect to the first portion 8A 1.
The first portion 8A 1 has a width substantially equal to the width of the fixing ring
10. The second portion 8A2 has a width smaller than the width ofthe fixing ring 10.
In this embodiment, both of the widths of the first and second portions 8A 1 and 8A2
are substantially constant with regard to the radial direction of the soundproofing
18
device 3 respectively, and a step 8S is formed in an inner wall of the groove 8A
between the first portion 8A 1 and the second portiop 8A2 ..
[0055]
The fixing ring 1 0 is fixed to the rim section 5 in a state of being in contact
with the step 8S. As a result of the second portion 8A2 having a width smaller than
the width of the fixing ring 10, the fixing ring 10 cannot move closer to a bottom
face ofthe groove 8A from a state of being in contact with the step 8S. Therefore,
in this state, the interval between the fixing ring 1 0 and the bottom face of the groove
8A is kept constant. This interval is set such that when vibration of a wheel is
transmitted to an additional mass section 12, the additional mass section 12 can
vibrate, and no gap will be generated between the second elastic body section 11 B
and the bottom of the groove 8A. As a result, it is possible that the first and second
elastic body sections llA, liB and the additional mass section 12, which constitute a
dynamic vibration absorber, vibrate at a predetermined resonance frequency.
[0056]
FIG. 7A is a sectional view of a soundproof wheel according to a fourth
variation ofthe embodiment shown in FIG. IA to FIG. 2. FIG. 7A shows a section
perpendicular to the central axis of a wheel. In FIG. 7 A, components corresponding
to the components shown in FIG. IA to FIG. 2 are given the same reference symbols
as those of FIG. 2, thus omitting description thereof.
[0057]
A protrusion 18A protruding from the outer peripheral surface of the fixing
ring 10 is provided between dynamic vibration absorbers 15 adjacent to each other in
the circumferential direction. The protrusion 18A is fixed to the fixing ring 10, and
extends to between the additional mass pieces 14 adjacent to each other in the
circumferential direction.
[0058]
The dynamic vibration absorber 15 and the protrusion 18A are sufficiently
spaced apart such that the dynamic vibration absorber 15 will not come into contact
with the protrusion 18A even when the dynamic vibration absorber 15 vibrates.
Therefore, there will be no case that the dynamic vibration absorber 15 and the
19
protrusion 18A come into contact with each other, impairing the function of the
dynamic vibration absorber 15.
[0059]
When the protrusion 18A is not provided, if the first and second elastic body
pieces 13A, 13B break off, problems arise in that as a result of the additional mass
piece 14 moving in the groove 8, abnormal noise occurs, and dynamic balance during
rotation ofthe wheel is disturbed. In the embodiment of FIG. 7A, such problems
can be prevented from occurring since the additional mass piece 14 is restricted from
moving in the circumferential direction of the wheel as a result of the protrusion 18A
being provided ..
[0060]
The protrusion 18A may be integral with the fixing ring 10, or a separate body.
When the protrusion 18A is a separate body from the fixing ring 10, the protrusion
18A may be made of, for example, the same material as that of the first elastic body
piece 13A. In this case, the first elastic body piece 13A and the protrusion 18A can
be formed collectively. Specifically, it is possible to form an first elastic body piece
13A and a protrusion 18A collectively by disposing a mold formed with concave
parts corresponding to the first elastic body piece 13A and the protrusion 18A over
the entire circumference on the outer peripheral surface of the fixing ring 10, poring
liquid precursor, which provides raw material for the first elastic body piece 13A and
the protrusion 18A, into the concave parts, and thereafter causing the precursor to be
hardened.
[0061]
In this production method, the liquid precursor may intrude into between the
outer peripheral surface of the fixing ring 10 and the mold, thereafter being hardened
as-is. In this case, the first elastic body piece 13A and the protrusion 18A will not
be separated completely, and is formed to be connected with a thin film of elastic
body. However, even in this case, each dynamic vibration absorber 15 has a
resonance frequency as designed and vibrates in a mutually independent manner.
That is, the plurality of first elastic body pieces 13A exhibit substantially same
behavior as in the case in which they are spaced apart from each other in the
20
circumferential direction of the fixing ring I 0. Therefore, each dynamic vibration
absorber can absorb vibration of a predetermined fryquency.
[0062]
FIG. 7B is a sectional view of a soundproof wheel according to a variation of
the embodiment shown in FIG. 7 A. FIG. 7B shows a section perpendicular to the
central axis of a wheel. In FIG. 7B, components corresponding to the components
shown in FIG. 7A are given the same reference symbols as those ofFIG. 7A, thus
omitting description thereof.
[0063]
A protrusion 18B protruding from the outer peripheral surface of the fixing
ring 10 is provided between dynamic vibration absorbers 15 adjacent to each other in
the circumferential direction. The protrusion 18B is fixed to the fixing ring 10, and
extends through between the additional mass pieces 14 adjacent to each other in the
circumferential direction. The distal end (the furthest portion from the outer
peripheral surface of the fixing ring 1 0) of the protrusion 18B is in contact with the
bottom face ofthe groove 8. As a result ofthe protrusion 18B being provided, it is
possible, as in the embodiment shown in FIG. 7A, to restrict the additional mass
piece 14 from moving in the circumference direction ofthe wheel when the first and
second elastic body pieces 13A, 13B break off, thereby suppressing occurrence of
abnormal noise, as well as making it easier to keep dynamic balance during rotation
ofthe wheel.
[0064]
The protrusion 18B may be integral with the fixing ring 1 0, or a separate body.
Moreover, this soundproof wheel may further include a ring-shape spacer member 16
(see FIG. 4) and in this case, the protrusion 18B may be integral with the spacer
member 16, or a separate body. In either case, the protrusion 18B is made of a high
rigidity material. As a result, the interval between the fixing ring 1 0 and the bottom
face of the groove 8 is kept constant. This interval is set such that when vibration
of a wheel is transmitted to an additional mass section 12, the additional mass piece
14 can vibrate, and no gap will be generated between the additional mass piece 14
and the bottom face ofthe groove 8 by the vibration ofthe additional mass piece 14
even when the second elastic body piece 13B is not stuck to the bottom ofthe groove
21
8. As a result, it is possible that the dynamic vibration absorber I5 vibrates at a
predetermined resonance frequency.
EXAMPLES
[0065]
A test using a wheel rolling noise tester was conducted on soundproof wheels
which were examples ofthe present invention, and wheels which were comparative
examples not satisfying part of the requirements of the present invention, to
investigate noise to be generated.
[0066]
As Examples I to 4, soundproof wheels I which each includes a
soundproofing device 3 having the structure shown in FIG. 2, and in which each
dynamic vibration absorber I5A to I5L was any of three types (TYPE-i to TYPE-iii)
having different resonance frequencies were fabricated. The natural frequencies of
the soundproof wheel I corresponding to major natural vibration modes of the wheel
2 were 2.0 kHz, 2.5 kHz, and 3.0 kHz.
[0067]
Table I shows resonance frequencies ofthe dynamic vibration absorbers I5 of
each type. Table 2 shows contents of the dynamic vibration absorbers of the
soundproof wheels of Examples, and the wheels of Comparative Examples.
22
[0068]
[Table 1]
TABLE I
Type of
soundproofing device
TYPE-i
TYPE-ii
TYPE-iii
[0069]
[Table 2]
~
Example I
Example 2
Example 3
Example 4
Comparative Example I
Comparative Example 2
Comparative Example 3
Comparative Example 4
Comparative Example 5
Resonance frequency
(kHz)
2.0
2.5
3.0
!SA 15B
TYPE-ii TYPE-i
TYPE-i TYPE-i
TYPE-ii TYPE-i
TYPE-i TYPE-i
- -
TYPE-i TYPE-i
TYPE-ii TYPE-ii
TYPE-iii TYPE-iii
- -
15C 15D 15E
TYPE-iii TYPE-ii TYPE-i
TYPE-iii TYPE-iii TYPE-ii
TYPE-iii TYPE-iii TYPE-i
TYPE-iii TYPE-iii TYPE-i
- - -
TYPE-i TYPE-i TYPE-i
TYPE-ii TYPE-ii TYPE-ii
TYPE-iii TYPE-iii TYPE-iii
- - -
TABLE 2
Soundproofing device
Remarks
!SF 15G ISH !51 15J 15K 15L
TYPE-iii TYPE-ii TYPE-i TYPE-iii TYPE-ii TYPE-i TYPE-iii
TYPE-ii TYPE-i TYPE-i TYPE-iii TYPE-iii TYPE-ii TYPE-ii I
Examples of the
TYPE-ii TYPE-ii TYPE-i TYPE-iii TYPE-iii TYPE-i TYPE-ii present invention
TYPE-i TYPE-ii TYPE-ii TYPE-iii TYPE-iii TYPE-ii TYPE-ii
- - - - - - - Without soundproofing device
TYPE-i TYPE-i TYPE-i TYPE-i TYPE-i TYPE-i TYPE-i
TYPE-ii TYPE-ii TYPE-ii TYPE-ii TYPE-ii TYPE-ii TYPE-ii
With only one kind bf
soundproofing device
TYPE-iii TYPE-iii TYPE-iii TYPE-iii TYPE-iii TYPE-iii TYPE-iii
Wheel according to/
- - - - - - - Patent Literature 2
23
[0070]
While four for each of the dynamic vibratiol} absorber 15 of_JYPE:i_~ the
dynamic vibration absorber 15 ofTYPE-ii, and the dynamic vibration absorber 15 of
TYPE-iii were used in any of Examples, positional relationships for the 3 types of
the dynamic vibration absorbers 15 were varied from each other among Examples 1
to 4.
[0071]
As Comparative Examples, an ordinary wheel (Comparative Example 1)
having no soundproofing device, a wheel (Comparative Example 2) in which all of
the dynamic vibration absorbers 15A to 15L were of TYPE-i, a wheel (Comparative
Example 3) in which all ofthe dynamic vibration absorbers 15A to 15L were of
TYPE-ii, a wheel (Comparative Example 4) in which all of the dynamic vibration
absorbers 15A to 15L were ofTYPE-iii, and a wheel (Comparative Example 5) in
which in place ofthe soundproofing device 3, a soundproof ring adopted in Patent
Literature 2 was mounted to the wheel 2 were prepared.
[0072]
FIG. 8 is a schematic diagram to show a configuration of a wheel rolling noise
tester used in the test.
[0073]
The wheel rolling noise tester 21 includes: a bearing 23, a hydraulic jack 24, a
rail wheel 25, a bearing 26, a motor 27, a precision noise meter 28, and a frequency
analyzer 29. The bearing 23 rotatably supports an axle 22 attached to a wheel 2
(soundproof wheel 1) to be tested. The hydraulic jack 24 was attached to the
bearing 23 to press the bearing 23 downward. The rail wheel 25 is configured to
abut against an outer peripheral portion of the wheel 2 supported by the bearing 23
through the axle 22, and to rotate the wheel 2. The bearing 26 supports the axle 22
attached to the rail wheel25. The motor 27 rotatively drives the axle 22 supported
by the bearing 26. The precision noise meter 28 measures noise generated from the
wheel 2 and generates an electric signal corresponding to the noise. The frequency
analyzer 29 receives input of the electric signal from the precision noise meter 28.
The frequency analyzer 29 performs frequency analysis of the electric signal.
[0074]
24
When performing test, the axle 22 attached to the wheel 2 and the axle 22
attached to the rail wheel 25 were arranged in parallel with each ot~_er; the Q_ttter
peripheral surface of the wheel 2 supported by the bearing 23 through the axle 22
was pressed against the outer peripheral surface of the rail wheel 25 supported by the
bearing 26 through the axle 22 by being driven by the hydraulic jack 24; and the rail
wheel 25 was rotated by the motor 27 in this state. As the result, the wheel 2 was
rotated.
[0075]
The precision noise meter 28 was disposed at a position 300 mm away from
the wheel 2, and generated noise was measured by the precision noise meter 28 by
rotating the soundproof wheels 1 of Examples and wheels of Comparative Examples
by the wheel rolling noise tester 21. The circumferential speed of the rail wheel 25
during noise measurement was supposed to be the rotational speed of the wheel 2 at
that time. The circumferential speed of the rail wheel 25 was determined from the
number of revolution of the motor 27 and the diameter of the rail wheel 25 (91 0 mm
in the wheel rolling noise tester 21 ). For example, when the number of revolution
ofthe motor 27 was 1750 rpm, the circumferential speed ofthe rail wheel 25 was
300 km/h.
[0076]
Noise measurement was performed by setting the precision noise meter 28 at
FLAT characteristics (without auditory correction) and FAST dynamic
characteristics. After the measurement by the precision noise meter 28, frequency
analysis of noise was performed by the frequency analyzer 29 based on the inputted
signal.
[0077]
FIG. 9 is a diagram to show noise correction levels to be used when analyzing
noise. After applying correction by the characteristic "A" of FIG. 9 on the
measured noise, 113 octave band processing was performed to determine frequency
characteristics and Overall values. The results are shown in FIGS. 10 to 13.
[0078]
FIG. 1 0 is a diagram showing the relationship between the 1/3 octave band
center frequency and the noise level for Examples 1 to 4 and Comparative Example 1.
25
FIG. 11 is a diagram showing the relationship between the 113 octave band center
frequency and the noise level for Comparative Examples Ito 5. _ The resuJts shown
in FIGS. 10 and 11 are those obtained when the rotational speed ofthe wheel2
(circumferential speed ofthe rail wheel25) was 200 km/h. Overall values (O.A.)
are shown at near the right end of FIGS. 10 and 11.
[0079]
From FIG. 10, it is seen that all of the soundproof wheels 1 of Examples 1 to
4 were able to significantly reduce noise around 2.0 kHz, 2.5 kHz, and 3.0 kHz
compared with Comparative Examples 1, that is, the case without any soundproofing
device. There was no significant difference observed among Examples 1 to 4.
That is, there was substantially no difference in noise reduction effect due to the
disposition of the dynamic vibration absorbers 15 ofTYPE-i to TYPE-iii adopted in
Examples 1 to 4.
[0080]
In contrast to this, as obvious from FIG. 11, the wheels of Comparative
Examples 2 to 4 were only able to reduce noise around a frequency of one level of
the resonance frequencies of the dynamic vibration absorbers 15, and were not able
to reduce noise at other frequencies. The wheel of Comparative Example 5 showed
less noise reduction effect compared with the soundproof wheels 1 of Examples 1 to
4 at least in the overall value.
[0081]
FIG. 12 is a diagram showing the relationship between the circumferential
speed of the rail wheel25 and the noise level for Examples 1 to 4, and Comparative
Example 1. FIG. 13 is a diagram showing the relationship between the
circumferential speed of the rail wheel 25 and the noise level for Comparative
Examples 1 to 5. In FIGS. 12 and 13, the noise levels are shown by overall values.
[0082]
As shown in FIG. 12, compared with the wheel of Comparative Example 1,
that is, a wheel without any soundproofing device, the soundproof wheels 1 of
Examples 1 to 4 achieved a certain level of noise reduction. The amount of
reduction of noise was not less than 5 dB(A) in a low speed range in which the
26
circumferential speed ofthe rail wheel25 was not more than 130 km/h, and not less
than 3 dB(A) in a high speed range of not less than J 40 km/h .. __
[0083]
On the other hand, as shown in FIG. 13, there was substantially no noise
reduction effect observed in the wheels of Comparative Examples 2 to 5 compared
with the wheel of Comparative Example 1.
REFERENCE SIGNS LIST
[0084]
Soundproof wheel
2 Wheel
3, 3A, 3B Soundproofing device
5 Rim section
6 Inner peripheral surface
8, 8A Groove
10 Fixing ring
lOa Outer peripheral surface
llA First elastic body section
liB Second elastic body section
12 Additional mass section
13A First elastic body piece
13B Second elastic body piece
14 Additional mass piece
15, 15A to 15L, 15X, 15Y Dynamic vibration absorber
18A, 18B Protrusion

We claim:
1. A soundproof wheel for a railway vehicle, comprising . __
a soundproofing device mounted onto an inner peripheral surface of a rim
section of the wheel,
the soundproofing device including:
a fixing ring fixed to the rim section with at least an outer peripheral portion
of the fixing ring fitted in a groove formed along a circumferential direction in the
inner peripheral surface of the rim section;
a first elastic body section which is stuck to an outer peripheral surface of the
fixing ring, and is disposed within the groove;
an additional mass section which is stuck to a side of the first elastic body
section opposite to the fixing ring, and is disposed within the groove; and
a second elastic body section which is stuck to a side of the additional mass
section opposite to the first elastic body section and is provided in the groove in such
a way that no gap is formed between the second elastic body section and a bottom of
the groove, wherein
the first elastic body section includes a plurality of first elastic body pieces
which are spaced apart from each other in a circumferential direction of the fixing
ring,
the second elastic body section includes a plurality of second elastic body
pieces which are spaced apart from each other in the circumferential direction of the
fixing ring,
the additional mass section includes a plurality of additional mass pieces
which are spaced apart from each other in the circumferential direction of the fixing
ring, and each atlditional mass piece is stuck to any of the plurality of first elastic
body pieces, and any of the plurality of second elastic body pieces,
the wheel has multiple natural frequencies corresponding to multiple natural
vibration modes,
the soundproofing device includes a plurality of dynamic vibration absorbers,
each dynamic vibration absorber having the additional mass piece, and the first and
second elastic body pieces, which are stuck to the additional mass piece,
28
at least one dynamic vibration absorber of the plurality of dynamic vibration
absorbers has a resonance frequency different from_the resonance frequency of
another dynamic vibration absorber, and any of the resonance frequencies of the
plurality of dynamic vibration absorbers corresponds to any of the multiple natural
frequencies.
2. The soundproof wheel according to claim 1, wherein
a spacer member is provided between the second elastic body section and the
bottom of the groove.
3. The soundproof wheel according to claim 1 or 2, further comprising:
a protrusion interposed between the dynamic vibration absorbers adjacent to
each other, and protruding from the outer peripheral surface of the fixing ring.
4. The soundproof wheel according to claim 3, wherein
a distal end ofthe protrusion is in contact with the bottom of the groove.