U.S. patent application number 16/066022 was filed with the patent office on 2019-12-12 for pneumatic tire.
This patent application is currently assigned to Sumitomo Rubber Industries, Ltd.. The applicant listed for this patent is Sumitomo Rubber Industries, Ltd.. Invention is credited to Hiroshi ITO, Takahiro KAWACHI, Tetsuya MAEKAWA, Daiki MUKOUGUCHI, Keiichi NAKADERA, Masako NAKATANI, Shuichiro ONO, Tatsuhiro TANAKA, Subaru TOYA, Ayuko YAMADA.
Application Number | 20190375250 16/066022 |
Document ID | / |
Family ID | 62978958 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190375250 |
Kind Code |
A1 |
NAKATANI; Masako ; et
al. |
December 12, 2019 |
PNEUMATIC TIRE
Abstract
A pneumatic tire 1 includes a carcass 6 extending between bead
cores of bead portions via a tread portion 2 and sidewall portions,
and a belt layer 7 arranged on an outer side in a tire radial
direction of the carcass 6 and inside the tread portion 2. The
pneumatic tire 1 has a noise damper 20 arranged on an inner cavity
surface of the tread portion 2. Glass transition temperature of the
noise damper 20 is in a range of from -55 degrees Celsius to -45
degrees Celsius.
Inventors: |
NAKATANI; Masako; (Kobe-shi,
Hyogo, JP) ; KAWACHI; Takahiro; (Kobe-shi, Hyogo,
JP) ; YAMADA; Ayuko; (Kobe-shi, Hyogo, JP) ;
NAKADERA; Keiichi; (Kobe-shi, Hyogo, JP) ; ITO;
Hiroshi; (Kobe-shi, Hyogo, JP) ; ONO; Shuichiro;
(Kobe-shi, Hyogo, JP) ; MUKOUGUCHI; Daiki;
(Kobe-shi, Hyogo, JP) ; TANAKA; Tatsuhiro;
(Kobe-shi, Hyogo, JP) ; MAEKAWA; Tetsuya;
(Kobe-shi, Hyogo, JP) ; TOYA; Subaru; (Kobe-shi,
Hyogo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sumitomo Rubber Industries, Ltd. |
Kobe-shi, Hyogo |
|
JP |
|
|
Assignee: |
Sumitomo Rubber Industries,
Ltd.
Kobe-shi, Hyogo
JP
|
Family ID: |
62978958 |
Appl. No.: |
16/066022 |
Filed: |
December 12, 2017 |
PCT Filed: |
December 12, 2017 |
PCT NO: |
PCT/JP2017/044581 |
371 Date: |
June 25, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60C 1/00 20130101; B60C
9/08 20130101; B60C 5/00 20130101; B60C 9/18 20130101; B60C 19/002
20130101; B60C 11/00 20130101 |
International
Class: |
B60C 19/00 20060101
B60C019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 25, 2017 |
JP |
2017-010922 |
Claims
1. A pneumatic tire comprising a carcass extending between bead
cores of bead portions via a tread portion and sidewall portions,
and a belt layer arranged on an outer side in a tire radial
direction of the carcass and inside the tread portion, wherein a
porous noise damper is arranged on an inner cavity surface of the
tread portion, and glass transition temperature of the noise damper
is in a range of from -55 degrees Celsius to -45 degrees
Celsius.
2. The pneumatic tire according to claim 1, wherein density of the
noise damper is in a range of from 10 to 40 kg/m3.
3. The pneumatic tire according to claim 1, wherein volume V1 of
the noise damper is in a range of from 0.4% to 30% of total volume
V2 of a tire inner cavity.
4. The pneumatic tire according to claim 1, wherein tensile
strength of the noise damper is in a range of from 70 to 115
kPa.
5. The pneumatic tire according to claim 1, further comprising a
dumping rubber body having a width W1 in a tire axial direction in
a range of from 60% to 130% of a width W2 in the tire axial
direction of the belt layer and provided inside the tread
portion.
6. The pneumatic tire according to claim 5, wherein the damping
rubber body is arranged between the carcass and the belt layer.
7. The pneumatic tire according to claim 5 further comprising a
band layer arranged on an outer side in the tire radial direction
of the belt layer and inside the tread portion, wherein the damping
rubber body is arranged between the belt layer and the band
layer.
8. The pneumatic tire according to claim 5 further comprising a
band layer arranged on an outer side in the tire radial direction
of the belt layer and inside the tread portion, wherein the damping
rubber body is arranged on an outer side in the tire radial
direction of the band layer.
9. The pneumatic tire according to claim 1, wherein thickness in
the tire radial direction of the damping rubber body is not less
than 0.3 mm.
10. The pneumatic tire according to claim 1, wherein relationship
between hardness H1 of the damping rubber body and hardness H2 of a
tread rubber arranged on an outer side in the tire radial direction
of the belt layer is 0.5.ltoreq.H1/H2.ltoreq.1.0.
11. The pneumatic tire according to claim 1, wherein a loss tangent
tan .delta. at 0 degree Celsius of a tread rubber arranged on an
outer side in the tire radial direction of the belt layer is not
less than 0.4, and the loss tangent tan .delta. at 70 degrees
Celsius of the tread rubber is not more than 0.2.
12. The pneumatic tire according to claim 1, wherein a tread rubber
arranged on an outer side in the tire radial direction of the belt
layer is a rubber composition body having a value not less than 20,
the value being calculated by (1.4.times.carbon black content
(phr)+silica content (phr))/sulfur content (phr).
Description
TECHNICAL FIELD
[0001] The present invention relates to a pneumatic tire provided
with a noise damper on an inner cavity surface of a tread
portion.
BACKGROUND ART
[0002] Conventionally, as a technique for suppressing running noise
of a pneumatic tire, as disclosed in Patent Literature 1, a
pneumatic tire has been known in which a noise damper made of a
sponge material is arranged on the inner cavity surface of the
tread portion.
PRIOR ART DOCUMENT
Patent Literature
[0003] [Patent Literature 1] Japanese Patent Application
Publication No. 2009-292461
[0004] However, when running in cold weather, the noise damper
becomes hard, therefore, vibration energy of air cannot be
sufficiently converted to thermal energy, thereby, the effect of
decreasing the running noise is limited.
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] The present invention was made in view of the above, and a
primary object thereof is to provide a pneumatic tire capable of
suppressing the running noise even when running in cold
weather.
Means for Solving the Problem
[0006] The present invention is a pneumatic tire comprising a
carcass extending between bead cores of bead portions via a tread
portion and sidewall portions, and a belt layer arranged on an
outer side in a tire radial direction of the carcass and inside the
tread portion, wherein a porous noise damper is arranged on an
inner cavity surface of the tread portion, and glass transition
temperature of the noise damper is in a range of from -55 degrees
Celsius to -45 degrees Celsius.
[0007] In the pneumatic tire according to the present invention, it
is preferred that density of the noise damper is in a range of from
10 to 40 kg/m3.
[0008] In the pneumatic tire according to the present invention, it
is preferred that volume V1 of the noise damper is in a range of
from 0.4% to 30% of total volume V2 of a tire inner cavity.
[0009] In the pneumatic tire according to the present invention, it
is preferred that tensile strength of the noise damper is in a
range of from 70 to 115 kPa.
[0010] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a dumping
rubber body having a width W1 in a tire axial direction in a range
of from 60% to 130% of a width W2 in the tire axial direction of
the belt layer and provided inside the tread portion.
[0011] In the pneumatic tire according to the present invention, it
is preferred that the damping rubber body is arranged between the
carcass and the belt layer.
[0012] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a band layer
arranged on an outer side in the tire radial direction of the belt
layer and inside the tread portion, wherein the damping rubber body
is arranged between the belt layer and the band layer.
[0013] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a band layer
arranged on an outer side in the tire radial direction of the belt
layer and inside the tread portion, wherein the damping rubber body
is arranged on an outer side in the tire radial direction of the
band layer.
[0014] In the pneumatic tire according to the present invention, it
is preferred that thickness in the tire radial direction of the
damping rubber body is not less than 0.3 mm.
[0015] In the pneumatic tire according to the present invention, it
is preferred that relationship between hardness H1 of the damping
rubber body and hardness H2 of a tread rubber arranged on an outer
side in the tire radial direction of the belt layer is
0.5.ltoreq.H1/H2.ltoreq.1.0.
[0016] In the pneumatic tire according to the present invention, it
is preferred that a loss tangent tan .delta. at 0 degree Celsius of
a tread rubber arranged on an outer side in the tire radial
direction of the belt layer is not less than 0.4, and the loss
tangent tan .delta. at 70 degrees Celsius of the tread rubber is
not more than 0.2.
[0017] In the pneumatic tire according to the present invention, it
is preferred that a tread rubber arranged on an outer side in the
tire radial direction of the belt layer is a rubber composition
body having a value not less than 20, the value being calculated by
(1.4.times.carbon black content (phr)+silica content (phr))/sulfur
content (phr),
Advantageous Effects of the invention
[0018] According to the pneumatic tire of the present invention,
the noise damper is arranged on the inner cavity surface of the
tread portion, therefore, cavity resonance in a tire inner cavity
is suppressed, thereby, the running noise of the pneumatic tire is
decreased. Further, in the present invention, the glass transition
temperature of the noise damper is in a range of from -55 degrees
Celsius to -45 degrees Celsius, therefore, flexibility of the noise
damper at low temperature is maintained. Thereby, even when running
in cold weather, the noise damper effectively converts the
vibration energy of the air into thermal energy, therefore, the
running noise is sufficiently decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 a cross-sectional view of a pneumatic tire as an
embodiment of the present invention.
[0020] FIG. 2 a cross-sectional view of a pneumatic tire as another
embodiment of the present invention.
[0021] FIG. 3 a cross-sectional view of a pneumatic tire as yet
another embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] An embodiment of the present invention will now be described
in conjunction with accompanying drawings.
[0023] FIG. 1 is a tire meridian section passing through a tire
rotational axis of a pneumatic tire 1 in this embodiment in a
standard state. Here, the standard state is a state in which the
tire is mounted on a standard rim RM, inflated to a standard inner
pressure, and loaded with no tire load. Hereinafter, dimensions and
the like of various parts of the tire 1 are those measured under
the standard state, unless otherwise noted.
[0024] The "standard rim" is a wheel rim specified for the
concerned tire by a standard included in a standardization system
on which the tire is based, for example, the "normal wheel rim" in
JATMA, "Design Rim" in TRA, and "Measuring Rim" in ETRTO.
[0025] The "standard pressure" is air pressure specified for the
concerned tire by a standard included in a standardization system
on which the tire is based, for example, the "maximum air pressure"
in JATMA, maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS
COLD INFLATION PRESSURES" table in TRA, and "INFLATION PRESSURE" in
ETRTO. When the tire is for a passenger car, it is set to 200 kPa
uniformly in consideration of the actual use frequency and the
like.
[0026] As shown in FIG. 1, the pneumatic tire (hereinafter may be
simply referred to as "tire") 1 in this embodiment is provided with
a carcass 6 extending between bead cores 5 of bead portions 4 via a
tread portion 2 and sidewall portions 3, and a belt layer 7
arranged on an outer side in a tire radial direction of the carcass
6 and inside the tread portion 2. In this embodiment, a tire for a
passenger car is shown as the tire 1.
[0027] The carcass 6 is formed by a single carcass ply 6A, for
example. The carcass ply 6A includes a main body portion 6a
extending between the bead cores 5 and turned up portions 6b each
being turned up around respective one of the bead cores 5 from
inside to outside in a tire axial direction so as to be engaged
with the respective one of the bead cores 5. In the carcass ply 6A,
organic fiber cords made of an organic material such as aromatic
polyamide and rayon are used as carcass cords, for example. The
carcass cords are arranged at an angle in a range of from 70 to 90
degrees with respect to a tire equator C, for example. The carcass
ply 6A is formed by a plurality of the carcass cords covered with
topping rubber. Between the main body portion 6a and each of the
turned up portions 6b, a bead apex rubber 8 extending radially
outwardly from respective one of the bead cores 5 in a tapered
manner is arranged.
[0028] On an outer side of the carcass 6, a tread rubber Tg for
forming a ground contacting surface, sidewall rubbers Sg each for
forming an outer surface of respective one of the sidewall portions
3, bead rubbers Bg each for forming an outer surface of respective
one of the bead portions 4, and the like are arranged. On the other
hand, on an inner side of the carcass 6, an inner liner rubber Lg
for keeping tire inner pressure and the like are arranged.
[0029] The belt layer 7 in this embodiment is formed by two belt
plies 7A and 7B in which belt cords are arranged at an angle in a
range of from 15 to 45 degrees with respect to the tire equator C,
for example, and the belt plies 7A and 7B are overlapped in the
tire radial direction so that the belt cords of the belt ply 7A and
the belt cords of the belt ply 7B cross each other. For the belt
cords, steel, aramid, rayon or the like is suitably used, for
example. By covering a plurality of the belt cords with the topping
rubber, the belt plies 7A and 7B are formed.
[0030] The pneumatic tire 1 in this embodiment is provided with a
band layer 9 arranged on an outer side in the tire radial direction
of the belt layer 7. The band layer 9 includes a band ply 9A in
which band cords of an organic fiber, nylon cords in this
embodiment, are spirally wound at an angle not more than 10
degrees, preferably not more than 5 degrees with respect to the
tire circumferential direction.
[0031] The pneumatic tire 1 is provided with a noise damper 20
arranged on an inner cavity surface of the tread portion 2. The
noise damper 20 is made of a porous sponge material, for example.
The sponge material is a cavernous porous structure body including
not only a so-called sponge itself having interconnected cells
formed by foamed rubber or a synthetic resin but also a web body
formed of an animal fiber, a vegetable fiber, or a synthetic fiber
and the like integrally interwoven, for example. Further, the
"porous structure body" includes not only a body having the
interconnected cells but also a body having closed cells. For the
noise damper 20 in this embodiment, a sponge material made of
polyurethane having interconnected cells is used.
[0032] In the sponge material as described above, the pores on the
surface of or inside the sponge material convert vibration energy
of the vibrating air into thermal energy, therefore, the vibration
energy is consumed, thereby, sound (cavity resonance energy) is
decreased, therefore, the running noise of the pneumatic tire 1 is
decreased. Further, the sponge material is easy to deform such as
contraction, flexion, etc., therefore, deformation of the tire
during running is not substantially affected. Thereby, it is
possible that deterioration of steering stability is prevented.
Moreover, specific gravity of the sponge material is very small,
therefore, it is possible that deterioration of weight balance of
the tire is prevented.
[0033] As the sponge material, synthetic resin sponge such as ether
type polyurethane sponge, ester type polyurethane sponge,
polyethylene sponge, and rubber sponge such as chloroprene rubber
sponge (CR sponge), ethylene propylene rubber sponge (EDPM sponge),
nitrile rubber sponge (NBR sponge) can be preferably and suitably
used, and in particular, a polyurethane type or polyethylene type
sponge including an ether type polyurethane sponge is preferred
from the point of view of noise damping property, lightweight
property, controllability of foaming, durability, and the like.
[0034] The noise damper 20 has an elongated belt-like shape having
a bottom surface fixed to the inner cavity surface of the tread
portion 2 and extends in the tire circumferential direction. At
this time, outer end portions in the circumferential direction of
the noise damper may be in contact with each other to form a
substantially annular shape, or the outer end portions may be
spaced apart in the tire circumferential direction.
[0035] The noise damper 20 has substantially the same
cross-sectional shape at an arbitrary position in the tire
circumferential direction except for the outer end portions. In
order to prevent collapse and deformation during running, it is
preferred that the cross-sectional shape is a flat and horizontally
elongated shape in which a height is smaller than a width in the
tire axial direction. In particular, as in this embodiment, it is
preferred to have a concave groove 21 extending continuously in the
tire circumferential direction on a side of the radially inner
surface. The concave groove 21 increases a surface area of the
noise damper 20, therefore, it is possible that more resonance
energy is absorbed, and heat dissipation is increased, therefore,
it is possible that the temperature rise of the sponge material is
suppressed.
[0036] Glass transition temperature of the noise damper 20 is in a
range of from -55 degrees Celsius to -45 degrees Celsius, when the
above glass transition temperature is less than -55 degrees
Celsius, hardness at ordinary temperature is likely to be
decreased, therefore, it is possible that the durability is
affected. When the above glass transition temperature exceeds -45
degrees Celsius, flexibility of the noise damper 20 at low
temperature is impaired, therefore, it is possible that the
decrease of the running noise mentioned above becomes small. In the
pneumatic tire 1, the glass transition temperature of the noise
damper 20 is set within the range of from -55 degrees Celsius to
-45 degrees Celsius, therefore, the flexibility of the noise damper
at low temperature is maintained. Thereby, even when running in
cold weather, the noise damper 20 effectively converts the
vibration energy of the air into thermal energy, therefore, the
running noise is sufficiently decreased.
[0037] In this embodiment, a damping rubber body 30 is disposed
inside the tread portion 2. The damping rubber body 30 is arranged
between the carcass 6 and the belt layer 7. The damping rubber body
30 is formed of rubber different from the topping rubber included
in the carcass ply 6A and the belt ply 7A. A width W1 in the tire
axial direction of the damping rubber body 30 is in a range of from
60% to 130% of a width W2 in the tire axial direction of the belt
layer 7. In a more preferred embodiment, the width W1 of the
damping rubber body 30 is in a range of from 70% to 120% of the
width W2 of the belt layer 7. The damping rubber body 30 configured
as such suppresses the vibration of the carcass 6 and the belt
layer 7 without contributing to the weight increase of the
pneumatic tire 1, and in particular contributes to the reduction of
the running noise around 160 HZ. Note that if sufficient reduction
effect of the running noise can be obtained by the noise damper 20,
the damping rubber body 30 may be omitted.
[0038] It is preferred that a thickness T1 in the tire radial
direction of the damping rubber body 30 is not less than 0.3 mm. By
setting the thickness T1 to not less than 0.3 mm, the vibration of
the tread portion 2 is more effectively suppressed. Further, by
setting a maximum thickness in the tire radial direction of the
damping rubber body 30 in a range of from 4% to 20% of a maximum
thickness of the tread portion 2, it is possible that the
suppression of the running noise of the pneumatic tire 1 and
steering stability performance are easily obtained at the same
time.
[0039] It is preferred that the relationship between hardness H1 of
the damping rubber body 30 and hardness H2 of the tread rubber Tg
disposed on an outer side in the tire radial direction of the belt
layer 7 is 0.5.ltoreq.H1/H2.ltoreq.1.0. Here, "rubber hardness" is
defined as rubber hardness measured in accordance with Japanese
Industrial Standard JIS-K 6253 by a type-A durometer under an
environment of 23 degrees Celsius. By the damping rubber body 30
having the hardness H1 described above, the vibration of the tread
portion 2 is more effectively suppressed while ensuring durability
performance of the tread portion 2.
[0040] It is preferred that relationship between the hardness H1 of
the damping rubber body 30 and hardness H3 of the topping rubber
included in the carcass ply 6A and the belt ply 7A is
0.4.ltoreq.H1/H3.ltoreq.1.2. By the damping rubber body 30 of the
hardness H1, vibration of the tread portion 2 is more effectively
suppressed while securing the durability performance of the tread
portion 2.
[0041] More specifically, it is preferred that the hardness H1 of
the damping rubber body 30 is in a range of from 30 to 73 degrees.
With the damping rubber body 30 of hardness H1 configured as such,
it is possible that the running noise is easily suppressed and the
steering stability performance is improved while suppressing
manufacturing cost of the pneumatic tire 1. Further, more
specifically, it is preferred that the hardness H2 of the tread
rubber Tg is in a range of from 55 to 75 degrees. By the tread
rubber Tg of the hardness H2 configured as such, the rigidity of
the tread portion 2 is optimized, therefore, it is possible that
the steering stability is improved.
[0042] In the pneumatic tire 1 in which the noise damper 20 is
provided on the inner cavity surface of the tread portion 2, during
the puncture repair by using the puncture repair liquid, the
puncture repair liquid is locally absorbed in the noise damper 20,
therefore, it is possible that uniformity performance after the
repair is deteriorated. The term uniformity as used herein refers
to the uniformity of weight including the pneumatic tire 1, the
noise damper 20, and the puncture repair liquid. If such uniformity
is impaired, it is possible that running noise tends to become
large. Considering the uniformity performance after the puncture
repair, it is preferred that density of the noise damper 20 is not
less than 10 kg/m3. On the other hand, by the noise damper 20
having the density not more than 40 kg/m3, it is possible that the
running noise in the vicinity of 250 HZ in particular is decreased
without increasing the weight of the pneumatic tire 1.
[0043] It is preferred that the volume V1 of the noise damper 20 is
in a range of from 0.4% to 30% of total volume V2 of the tire inner
cavity. The volume V1 of the noise damper 20 is apparent total
volume of the noise damper 20, which means the volume determined
from the outer shape including the inner cells. The total volume V2
of the tire inner cavity is to be approximately determined by the
following formula with respect to a pneumatic tire in the standard
state in which the pneumatic tire is mounted on a standard rim,
inflated to the standard inner pressure, and loaded with no tire
load.
V2=A.times.{(Di-Dr)/2+Dr}.times..pi.
In the above formula, "A" is a cross sectional area of the tire
inner cavity obtained by CT scanning a tire/rim assembly in the
standard state, "Di" is a maximum outer diameter of the inner
cavity surface of the tire in the standard state, "Dr" is a
diameter of the rim, and ".pi." is the circumference ratio.
[0044] If the volume V1 is less than 0.4% of the total volume V2,
it is possible that the vibration energy of the air is not
sufficiently converted. If the volume V1 is more than 30% of the
total volume V2, it is possible that the weight and the
manufacturing cost of the pneumatic tire 1 increases. Further, in
the puncture repair by using the puncture repair liquid, it is
possible that the uniformity performance after the repair is
deteriorated.
[0045] It is preferred that tensile strength of the noise damper 20
is in a range of from 70 to 115 kPa. If the tensile strength of the
noise damper 20 is less than 70 kPa, it is possible that the
durability performance of the noise damper 20 deteriorates. If the
tensile strength of the noise damper 20 is more than 115 kPa, when
a foreign object such as a nail sticks into the region including
the noise damper 20 of the tread portion 2, the noise damper 20 may
be pulled by the foreign object, therefore, it is possible that the
noise damper 20 comes off the inner cavity surface of the tread
portion 2.
[0046] It is preferred that a loss tangent tan .delta. at 0 degree
Celsius of the tread rubber Tg is not less than 0.4. Thereby, wet
grip performance of the pneumatic tire 1 is improved. Therefore, by
setting the volume of the grooves formed in the ground contacting
surface of the tread portion 2 to be small and the like, it is
possible to further reduce the running noise, for example. It is
preferred that the loss tangent tan .delta. at 70 degrees Celsius
of the tread rubber Tg is not more than 0.2. Thereby, rolling
resistance of the pneumatic tire 1 is suppressed and deterioration
of the fuel efficiency due to inclusion of the noise damper 20 and
the damping rubber body 30 is suppressed. Note that the loss
tangent tan .delta. at 0 degrees Celsius and the loss tangent tan
.delta. at 70 degrees Celsius were measured in accordance with
Japanese Industrial Standard JIS-K 6394 by using a viscoelasticity
spectrometer available from Iwamoto Quartz GlassLab Co., Ltd. under
a condition of respective temperature (0 degrees Celsius or 70
degrees Celsius), a frequency of 10 Hz, an initial tensile strain
of 10%, and an amplitude of dynamic strain of .+-.2%.
[0047] It is preferred that a value calculated by a following
formula: (1.4.times.carbon black content (phr)+silica content
(phr))/sulfur content (phr) of the tread rubber Tg, is not less
than 20. Thereby, anti-wear performance is improved. Therefore, by
setting depths of the grooves formed in the ground contacting
surface of the tread portion 2 to be small and the like, it is
possible that the running noise is further decreased, for example.
Further, even when distribution of the puncture repair liquid is
not uniform, occurrence of uneven wear is suppressed.
[0048] While detailed description has been made of the pneumatic
tire of the present invention, the present invention can be
embodied in various forms without being limited to the illustrated
embodiment.
[0049] FIG. 2 shows a pneumatic tire 1A as another embodiment of
the present invention, for example. The pneumatic tire 1A is
different from the pneumatic tire 1 in that the damping rubber body
30 is disposed between the belt layer 7 and the band layer 9. The
configuration of the pneumatic tire 1 can be applied to the
components of the pneumatic tire 1A that are not described below.
In the pneumatic tire 1A, the vibration of the belt layer 7 and the
band layer 9 is suppressed by the damping rubber body 30,
therefore, the vibration of the tread portion 2 is suppressed
eventually.
[0050] FIG. 4 shows a pneumatic tire 18 as yet another embodiment
of the present invention. The pneumatic tire 1B is different from
the pneumatic tire 1 in that the damping rubber body 30 is arranged
on an outer side in the tire radial direction of the band layer 9.
The configuration of the pneumatic tire 1 can be applied to the
components of the pneumatic tire 1B that are not described below.
In the pneumatic tire 1B, the vibration of the band layer 9 and the
tread rubber Tg is suppressed by the damping rubber body 30,
therefore, the vibration of the tread portion 2 is suppressed
eventually.
WORKING EXAMPLES
[0051] Pneumatic tires of size 165/65R18 having the basic structure
shown in FIG. 1 were made by way of test according to the
specification listed in Table 1, then the test tires were tested
for the noise performance under low temperature environment. The
specifications common to each of examples and References were as
follows.
(1) Tread Rubber
[0052] The formulations were as follows.
[0053] Natural rubber (TSR20): 15 (phr)
[0054] SBR 1 (bound styrene content: 28%, vinyl group content: 60%,
glass transition point: -25 degrees Celsius, terminal modified): 45
(phr)
[0055] SBR 2 (bound styrene content: 35%, vinyl group content: 45%,
glass transition point: -25 degrees Celsius, terminal modified): 25
(phr)
[0056] BR (BR1508 available from Ube Industries, Ltd.): 15
(phr)
[0057] Carbon black N220: 5 (phr)
[0058] Silica (VN3): 35 (phr)
[0059] Silica (1115MP): 20 (phr)
[0060] Silane coupling agent Si266: 4 (phr)
[0061] Resin (SYLVARES SA85 available from Arizona Chemical
Company): 8 (phr)
[0062] Oil: 4 (phr)
[0063] Wax: 1.5 (phr)
[0064] Age resistor (6C): 3 (phr)
[0065] Stearic acid: 3 (phr)
[0066] Zinc oxide: 2 (phr)
[0067] Sulfur: 2 (phr)
[0068] Vulcanization accelerator (NS): 2 (phr)
[0069] Vulcanization accelerator (DPG): 2 (phr) [0070] The hardness
of the tread rubber of the vulcanized tire was 64 degrees. [0071]
The maximum thickness of the tread rubber was 10 mm.
(2) Damping Rubber Body
[0071] [0072] The formulations were as follows.
[0073] Natural rubber (TSR20): 65 (phr)
[0074] SBR (Nipol 1502): 35 (phr)
[0075] Carbon black N220: 52 (phr)
[0076] Oil: 15 (phr)
[0077] Stearic acid: 1.5 (phr)
[0078] Zinc oxide: 2 (phr)
[0079] Sulfur: 3 (phr)
[0080] Vulcanization accelerator (CZ): 1 (phr) [0081] The hardness
of the damping rubber body of the vulcanized tire was 58 degrees.
[0082] The maximum thickness of the damping rubber body was 1
mm.
(3) Noise Damper
[0082] [0083] The volume was 15% of the total volume of the tire
inner cavity. [0084] The density was 27 kg/m3.
(4) Belt Cords
[0084] [0085] The angle of the belt cords with respect to the tire
equator was 41 degrees. [0086] The test methods were as
follows.
[0087] Each of the test tires was mounted on a rim of 18.times.7JJ
and brought into a laboratory in which the room temperature is set
at -50 degrees Celsius. Each of the test tires was run at a speed
of 60 km/h on a drum having a replica road surface with a diameter
of 3.3 m under conditions of an internal pressure of 320 kPa and a
load of 4.8 kN, and 25 mm in front and 25 mm in height The sound
pressure level (dB) at the spaced position was measured by a
microphone. The results are indicated by an index based on Example
1 being 100, wherein the larger the numerical value, the smaller
the running noise is, which is better.
TABLE-US-00001 TABLE 1 Ref.1 Ref.2 Ex.1 Ex.2 Ex.3 Presence or
Absence of Noise damper absence presence presence presence presence
Glass transition temperature of Noise damper -- -30 -50 -55 -45
[degree Celsius] Presence or Absence of Damping rubber body absence
absence absence absence absence Noise performance [index] 80 85 100
100 95
[0088] As is apparent from Table 1, it was confirmed that the noise
performance in the low temperature environment of the pneumatic
tires as Examples 1 to 3 was significantly improved as compared
with References 1 and 2.
[0089] Further, as shown in Table 2, the pneumatic tires as
Examples 4 to 8 were made by way of test and the noise performance
under the low temperature environment was tested. The test method
was as follows.
<Noise Performance>
[0090] Sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 5 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00002 TABLE 2 Ex.4 Ex.5 Ex.6 Ex.7 Ex.8 Presence or Absence
of Noise damper presence presence presence presence presence Glass
transition temperature of Noise damper -50 -50 -50 -50 -50 [degree
Celsius] Presence or Absence of Damping rubber body absence
presence presence presence presence width w1 of Damping rubber
body/width -- 100 80 70 130 w2 of Belt layer [%] Noise performance
[index] 90 100 95 98 105
[0091] Further, as shown in Table 3, the pneumatic tires as
Examples 9 to 12 were made by way of test and the noise performance
under the low temperature environment and the steering stability
performance were tested. The test methods were as follows.
<Noise Performance>
[0092] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 11 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
<Steering Stability Performance>
[0093] Each of the test tires was mounted on a rim of 18'7JJ,
mounted on all wheels of a car (domestically produced FR car with
displacement of 2500 cc) under the condition of the inner pressure
of 320 kPa, and then, while the car was driven on a dry asphalt
test course, characteristics related to steering response, rigid
impression, grip, and the like were evaluated by the driver's
feeling. The results are indicated by an evaluation point based on
the Example 11 being 100, wherein a larger numerical value is
better.
TABLE-US-00003 TABLE 3 Ex.9 Ex.10 Ex.11 Ex.12 Presence or Absence
of Noise damper presence presence presence presence Glass
transition temperature of Noise -50 -50 -50 -50 damper [degree
Celsius] Presence or Absence of Damping presence presence presence
presence rubber body width w1 of Damping rubber body/ 100 100 100
100 width w2 of Belt layer [%] Thickness T1 of Damping rubber 0.2
0.3 0.5 0.7 body [mm] Noise performance [index] 98 99 100 103
Steering stability [index] 100 100 100 98
[0094] Furthermore, as shown in Table 4, the pneumatic tires as
Examples 13 to 17 having the damping rubber body of different
rigidity were made by way of test, and then the noise performance
under the low temperature environment was tested and the
manufacturing cost was calculated. The test method and the
calculation method were as follows.
<Noise Performance>
[0095] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 15 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
<Manufacturing Cost>
[0096] Manufacturing cost required to manufacture a single tire was
calculated. The results are indicated by an index based on the
example 15 being 100, wherein the larger the numerical value, the
smaller the manufacturing cost is, which is better.
TABLE-US-00004 TABLE 4 Ex.13 Ex.14 Ex.15 Ex.16 Ex.17 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
presence presence presence presence presence width w1 of Damping
rubber body/width 100 100 100 100 100 w2 of Belt layer [%] Hardness
H1 of Damping rubber body/ 0.4 0.5 0.7 1.0 1.2 Hardness H2 of Tread
rubber Noise performance [index] 96 98 100 102 102 Manufacturing
cost [index] 102 102 100 98 86
[0097] Furthermore, as shown in Table 5, the pneumatic tires as
Examples 18 to 22 were made by way of test, and then the uniformity
performance after the puncture repair and the noise performance
under the low temperature environment were tested. The test methods
were as follows.
<Uniformity Performance>
[0098] Each of the test tires was mounted on a rim of 18.times.7JJ
and injected with puncture repair material simulating puncture
repair, and then radial force variation (RFV) was measured under
the condition of the inner pressure of 320 kPa in accordance with
uniformity test condition of Japanese Automobile Standards
Organization JASO C607:2000. The evaluation speed was 10 km/h. The
results are indicated by an index based on the example 20 being
100, wherein the larger the numerical value, the smaller the RFV
is, which is better.
<Noise Performance>
[0099] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 20 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00005 TABLE 5 Ex.18 Ex.19 Ex.20 Ex.21 Ex.22 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
presence presence presence presence presence width w1 of Damping
rubber body/width 100 100 100 100 100 w2 of Belt layer [%] Density
of Noise damper [kg/m3] 5 10 27 40 50 Uniformity performance
[index] 95 97 100 103 103 Noise performance [index] 103 103 100 97
95
[0100] Furthermore, as shown in Table 6, the pneumatic tires as
Examples 23 to 27 were made by way of test, and then the uniformity
performance after the puncture repair and the noise performance
under the low temperature environment were tested. The test methods
were as follows.
<Uniformity Performance>
[0101] The RFV was measured by the same method as described above.
The results are indicated by an index based on the Example 25 being
100, wherein the larger the numerical value, the smaller the RFV
is, which is better.
<Noise Performance>
[0102] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 25 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00006 TABLE 6 Ex.23 Ex.24 Ex.25 Ex.26 Ex.27 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
presence presence presence presence presence width w1 of Damping
rubber body/width 100 100 100 100 100 w2 of Belt layer [%] volume
v1 of Noise damper/Total volume v2 0.3 0.4 15.0 30.0 35.0 of Tire
inner cavity [%] Uniformity performance [index] 103 103 100 97 95
Noise performance [index] 95 97 100 103 103
[0103] Furthermore, as shown in Table 7, the pneumatic tires as
Examples 28 to 32 were made by way of test, and then the durability
performance of the noise damper and separation resistance
performance of the noise damper when a nail sticks were tested. The
test methods were as follows.
Durability Performance of Noise Damper>
[0104] Each of the test tires was mounted on a rim of 16.times.7JJ
and then, by using a drum testing machine, a distance until the
noise damper and its vicinity were damaged was measured under the
conditions of the inner pressure of 320 kPa, the tire load of 4.8
kN, and the speed of 80 km/h. The results are indicated by an index
based on the Example 30 being 100, wherein the larger the numerical
value, the higher the durability is, which is better.
<Separation Resistance Performance of Noise Damper when Nail
Sticks>
[0105] Each of the test tires was mounted on a rim of 18.times.7JJ
and punctured by rolling on a nail, then the damaged part was
disassembled to measure the area of separation of the noise damper
from the inner cavity surface of the tread portion due to the noise
damper being pulled by the nail. The results are indicated by an
index based on the Example 30 being 100, wherein the larger the
numerical value, the higher the separation resistance performance
is, which is better.
TABLE-US-00007 TABLE 7 Ex.28 Ex.29 Ex.30 Ex.31 Ex.32 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
presence presence presence presence presence width w1 of Damping
rubber body/width 100 100 100 100 100 w2 of Belt layer [%] Tensile
strength of Noise damper [kPa] 60 70 90 115 125 Durability of Noise
damper [index] 95 97 100 103 103 Separation resistance performance
of 103 103 100 97 95 Noise damper when Nail sticks [index]
[0106] Furthermore, as shown in Table 8, the pneumatic tires as
Examples 33 to 35 were made by way of test, and then the noise
performance under the low temperature environment was tested. The
test method was as follows.
<Noise Performance>
[0107] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 1 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00008 TABLE 8 Ex.33 Ex.34 Ex.35 Presence or Absence of
Noise damper presence presence presence Glass transition
temperature of Noise damper -50 -55 -45 [degree Celsius] Presence
or Absence of Damping rubber body presence presence presence width
w1 of Damping rubber body/width 100 100 100 w2 of Belt layer [%]
Noise performance [index] 110 110 105
[0108] Furthermore, as shown in Table 9, the pneumatic tires as
Examples 36 to 40 were made by way of test, and then the uniformity
performance after the puncture repair and the noise performance
under the low temperature environment were tested. The test methods
were as follows.
<Uniformity Performance>
[0109] The radial force variation (RFV) was measured by the same
method as described above. The results are indicated by an index
based on the Example 20 being 100, wherein the larger the numerical
value, the smaller the RFV is, which is better.
<Noise Performance>
[0110] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 20 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00009 TABLE 9 Ex.36 Ex.37 Ex.38 Ex.39 Ex.40 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
absence absence absence absence absence Density of Noise damper
[kg/m3] 5 10 27 40 50 Uniformity performance [index] 95 97 100 103
103 Noise performance [index] 95 95 92 89 87
[0111] Furthermore, as shown in Table 10, the pneumatic tires as
Examples 41 to 45 were made by way of test, and then the uniformity
performance after the puncture repair and the noise performance
under the low temperature environment were tested. The test methods
were as follows.
<Uniformity Performance>
[0112] The radial force variation (RFV) was measured by the same
method as described above. The results are indicated by an index
based on the Example 25 being 100, wherein the larger the numerical
value, the smaller the RFV is, which is better.
<Noise Performance>
[0113] The sound pressure level was measured by the same method as
described above. The results are indicated by an index based on the
Example 25 being 100, wherein the larger the numerical value, the
smaller the running noise is, which is better.
TABLE-US-00010 TABLE 10 Ex.41 Ex.42 Ex.43 Ex.44 Ex.45 Presence or
Absence of Noise damper presence presence presence presence
presence Glass transition temperature of Noise damper -50 -50 -50
-50 -50 [degree Celsius] Presence or Absence of Damping rubber body
absence absence absence absence absence volume v1 of Noise
damper/Total volume v2 0.3 0.4 15.0 30.0 35.0 of Tire inner cavity
[%] Uniformity performance [index] 103 103 100 97 95 Noise
performance [index] 87 88 92 95 95
DESCRIPTION OF THE REFERENCE SIGNS
[0114] 1 pneumatic tire [0115] 2 tread portion [0116] 3 sidewall
portion [0117] 4 bead portion [0118] 5 bead core [0119] 6 carcass
[0120] 20 noise damper [0121] 30 damping rubber body
* * * * *