U.S. patent application number 16/080210 was filed with the patent office on 2020-05-28 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 Takuya HORIGUCHI, Nanaho KAMI, Takahiro KAWACHI, Masako NAKATANI, Keiji TAKAGI, Tatsuhiro TANAKA, Subaru TOYA, Ayuko YAMADA.
Application Number | 20200164700 16/080210 |
Document ID | / |
Family ID | 62710942 |
Filed Date | 2020-05-28 |
United States Patent
Application |
20200164700 |
Kind Code |
A1 |
NAKATANI; Masako ; et
al. |
May 28, 2020 |
PNEUMATIC TIRE
Abstract
To be capable of preventing deterioration of uniformity after
puncture repair while suppressing running noise. [Solution] A
pneumatic tire 1 comprises a noise damper 20 fixed to a tire inner
cavity surface of a tread portion 2 and formed of a porous
material. The noise damper 20 includes a first part 23 arranged on
an outer side in a tire radial direction and fixed to the tire
inner cavity surface 16, and a second part 24 arranged on an inner
side in the tire radial direction of the first part 23 and exposed
in a tire inner cavity 17. A water absorption rate of the first
part 23 calculated by a following formula (1) is in a range of from
5% to 25%. Air permeability of the second part 24 measured in
accordance with Japanese Industrial standard JIS-L1096 is in a
range of from 1 to 7 cm3/cm2/s. The formula (1) is: water
absorption rate (%)=weight change before and after immersion
(g)/volume at 50% compression (cm3).times.100 (1).
Inventors: |
NAKATANI; Masako; (Kobe-shi,
Hyogo, JP) ; KAWACHI; Takahiro; (Kobe-shi, Hyogo,
JP) ; KAMI; Nanaho; (Kobe-shi, Hyogo, JP) ;
YAMADA; Ayuko; (Kobe-shi, Hyogo, JP) ; HORIGUCHI;
Takuya; (Kobe-shi, Hyogo, JP) ; TANAKA;
Tatsuhiro; (Kobe-shi, Hyogo, JP) ; TAKAGI; Keiji;
(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: |
62710942 |
Appl. No.: |
16/080210 |
Filed: |
December 6, 2017 |
PCT Filed: |
December 6, 2017 |
PCT NO: |
PCT/JP2017/043851 |
371 Date: |
August 27, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60C 11/0008 20130101;
C08K 3/04 20130101; B60C 19/12 20130101; B60C 1/00 20130101; B60C
19/002 20130101; C08K 3/06 20130101; B60C 11/00 20130101; B60C
1/0016 20130101; B60C 2009/1878 20130101; B60C 5/00 20130101; B60C
9/18 20130101; C08K 3/36 20130101; B60C 5/002 20130101; B60C
2011/0025 20130101 |
International
Class: |
B60C 19/00 20060101
B60C019/00; B60C 1/00 20060101 B60C001/00; B60C 9/18 20060101
B60C009/18; B60C 11/00 20060101 B60C011/00; C08K 3/04 20060101
C08K003/04; C08K 3/06 20060101 C08K003/06; C08K 3/36 20060101
C08K003/36 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2016 |
JP |
2016-256342 |
Claims
1. A pneumatic tire comprising a noise damper fixed to a tire inner
cavity surface of a tread portion and formed of a porous material,
wherein the noise damper includes a first part arranged on an outer
side in a tire radial direction and fixed to the tire inner cavity
surface, and a second part arranged on an inner side in the tire
radial direction of the first part and exposed in a tire inner
cavity, a water absorption rate of the first part is in a range of
from 5% to 25%, the water absorption rate being calculated by a
following formula (1): water absorption rate (%)=weight change
before and after immersion (g)/volume at 50% compression
(cm3).times.100 (1), and air permeability of the second part
measured in accordance with Japanese Industrial Standard JIS-L1096
is in a range of from 1 to 7 cm3/cm2/s.
2. The pneumatic tire according to claim 1, wherein density of the
first part is in a range of from 15 to 30 kg/m3, and density of the
second part is in a range of from 20 to 35 kg/m3.
3. The pneumatic tire according to claim 1, wherein total volume V1
of the noise damper is in a range of from 0.4% to 30% of total
volume V2 of the tire inner cavity.
4. The pneumatic tire according to claim 1 further comprising a
carcass extending between a pair of bead portions, a belt layer
arranged on an outer side in the tire radial direction of the
carcass and inside the tread portion, and a damping rubber body
arranged inside the tread portion and on an inner or outer side in
the tire radial direction of the belt layer, wherein a width W1 in
a tire axial direction of the damping rubber body is in a range of
from 60% to 130% of a width W2 in the tire axial direction of the
belt layer.
5. The pneumatic tire according to claim 4, wherein a ratio (H1/H2)
of hardness H1 of the damping rubber body and hardness H2 of a
tread rubber arranged in the tread portion is in a range of from
0.5 to 1.0.
6. The pneumatic tire according to claim 1 further comprising a
tread rubber arranged in the tread portion, wherein a loss tangent
tan .delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
7. The pneumatic tire according to claim 1 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
8. The pneumatic tire according to claim 2, wherein total volume V1
of the noise damper is in a range of from 0.4% to 30% of total
volume V2 of the tire inner cavity.
9. The pneumatic tire according to claim 2 further comprising a
carcass extending between a pair of bead portions, a belt layer
arranged on an outer side in the tire radial direction of the
carcass and inside the tread portion, and a damping rubber body
arranged inside the tread portion and on an inner or outer side in
the tire radial direction of the belt layer, wherein a width W1 in
a tire axial direction of the damping rubber body is in a range of
from 60% to 130% of a width W2 in the tire axial direction of the
belt layer.
10. The pneumatic tire according to claim 3 further comprising a
carcass extending between a pair of bead portions, a belt layer
arranged on an outer side in the tire radial direction of the
carcass and inside the tread portion, and a damping rubber body
arranged inside the tread portion and on an inner or outer side in
the tire radial direction of the belt layer, wherein a width W1 in
a tire axial direction of the damping rubber body is in a range of
from 60% to 130% of a width W2 in the tire axial direction of the
belt layer.
11. The pneumatic tire according to claim 2 further comprising a
tread rubber arranged in the tread portion, wherein a loss tangent
tan .delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
12. The pneumatic tire according to claim 3 further comprising a
tread rubber arranged in the tread portion, wherein a loss tangent
tan .delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
13. The pneumatic tire according to claim 4 further comprising a
tread rubber arranged in the tread portion, wherein a loss tangent
tan .delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
14. The pneumatic tire according to claim 5 further comprising a
tread rubber arranged in the tread portion, wherein a loss tangent
tan .delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
15. The pneumatic tire according to claim 2 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
16. The pneumatic tire according to claim 3 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
17. The pneumatic tire according to claim 4 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
18. The pneumatic tire according to claim 5 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
19. The pneumatic tire according to claim 6 further comprising a
tread rubber arranged in the tread portion, wherein the tread
rubber contains carbon black, silica, and sulfur, and a content A1
(phr) of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 (2).
Description
TECHNICAL FIELD
[0001] The present invention relates to a pneumatic tire in which a
noise damper is disposed on a tire inner cavity surface.
BACKGROUND ART
[0002] In order to suppress running noise of a pneumatic tire,
Patent Literature 1 shown below proposes a pneumatic tire in which
a noise damper made of a porous material is fixed to a tire inner
cavity surface of a tread portion.
[0003] On the other hand, as a method of repairing a punctured
pneumatic tire, a method of injecting puncture repair liquid for
sealing the puncture hole in a tire inner cavity is known. In such
a repair method, in order to spread the repair liquid into the
puncture hole, it is necessary to position the puncture hole
downward (on a side of the ground) prior to injection of the
puncture repair liquid.
Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2009-292461
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0004] When the puncture repair liquid is injected in the pneumatic
tire of the above Patent Literature 1, the puncture repair liquid
may be absorbed more than necessary in the noise damper near the
puncture hole. In such a case, even if the pneumatic tire is
rotated after injecting the puncture repair liquid, the puncture
repair liquid is not uniformly distributed in a tire
circumferential direction. Therefore, it is possible that
uniformity of the pneumatic tire after puncture repair is
deteriorated. The term "uniformity" as used herein refers to the
uniformity of weight including the pneumatic tire, the noise
damper, and the puncture repair liquid. If such uniformity is
impaired, it is possible that running noise tends to become
large.
[0005] Further, in order to efficiently seal the puncture hole
formed in the inner cavity surface of the tread portion, the
pneumatic tire of the above Patent Literature 1 is provided with a
repair liquid permeable layer between the noise damper and the
inner cavity surface of the tread portion. The repair liquid
permeable layer increases an absorption rate of the puncture repair
liquid by decreasing flow resistance and increasing porosity.
However, such a repair liquid permeable layer further absorbs the
puncture repair liquid near the puncture hole, therefore, it is
possible that the distribution of the puncture repair liquid
becomes more ununiform.
[0006] The present invention was made in view of the above, and a
primary object thereof is to provide a pneumatic tire capable of
preventing deterioration of the uniformity after puncture repair
while suppressing the running noise.
Means for Solving the Problem
[0007] The present invention is a pneumatic tire comprising a noise
damper fixed to a tire inner cavity surface of a tread portion and
formed of a porous material, wherein the noise damper includes a
first part arranged on an outer side in a tire radial direction and
fixed to the tire inner cavity surface, and a second part arranged
on an inner side in the tire radial direction of the first part and
exposed in a tire inner cavity, a water absorption rate of the
first part is in a range of from 5% to 25%, the water absorption
rate being calculated by a following formula (1): water absorption
rate (%)=weight change before and after immersion (g)/volume at 50%
compression (cm3).times.100 (1), and air permeability of the second
part measured in accordance with Japanese Industrial standard
JIS-L1096 is in a range of from 1 to 7 cm3/cm2/s.
[0008] In the pneumatic tire according to the present invention, it
is preferred that density of the first part is in a range of from
15 to 30 kg/m3, and density of the second part is in a range of
from 20 to 35 kg/m3.
[0009] In the pneumatic tire according to the present invention, it
is preferred that total volume V1 of the noise damper is in a range
of from 0.4% to 30% of total volume V2 of the tire inner
cavity.
[0010] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a carcass
extending between a pair of bead portions, a belt layer arranged on
an outer side in the tire radial direction of the carcass and
inside the tread portion, and a damping rubber body arranged inside
the tread portion and on an inner or outer side in the tire radial
direction of the belt layer, wherein a width W1 in a tire axial
direction of the damping rubber body is in a range of from 60% to
130% of a width W2 in the tire axial direction of the belt
layer.
[0011] In the pneumatic tire according to the present invention, it
is preferred that a ratio (H1/H2) of hardness H1 of the damping
rubber body and hardness H2 of a tread rubber arranged in the tread
portion is in a range of from 0.5 to 1.0.
[0012] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a tread
rubber arranged in the tread portion, wherein a loss tangent tan
.delta. at zero degrees Celsius of the tread rubber is not less
than 0.40 and the loss tangent tan .delta. at 70 degrees Celsius of
the tread rubber is not more than 0.20.
[0013] In the pneumatic tire according to the present invention, it
is preferred that the pneumatic tire further comprises a tread
rubber arranged in the tread portion, wherein the tread rubber
contains carbon black, silica, and sulfur, and a content A1 (phr)
of the carbon black, a content A2 (phr) of the silica, and a
content A3 (phr) of the sulfur satisfy relation of a following
formula (2): (1.4.times.A1+A2)/A3.gtoreq.20 . . . (2).
Advantageous Effects of the Invention
[0014] The pneumatic tire according to the present invention
comprises the noise damper fixed to the tire inner cavity surface
of the tread portion and formed of the porous material. The noise
damper configured as such can suppress cavity resonance, therefore,
it is possible that the running noise of the pneumatic tire is
decreased.
[0015] The noise damper includes the first part arranged on the
outer side in the tire radial direction and fixed to the tire inner
cavity surface, and the second part arranged on the inner side in
the tire radial direction of the first part and exposed in the tire
inner cavity.
[0016] The water absorption rate of the first part calculated by
the above formula (1) is set to be in a range of from 5% to 25%.
The water absorption rate of the first part configured as such is
small as compared with the water absorption rate of the repair
liquid permeable layer of the above Patent Literature 1. Thereby,
it is possible that the first part prevents the puncture repair
liquid from being absorbed more than necessary. Therefore, in the
pneumatic tire according to the present invention, it is possible
that the puncture repair liquid is uniformly distributed in the
tire circumferential direction by the rotation of the tire after
the injection of the puncture repair liquid. Thereby, the pneumatic
tire according to the present invention can prevent deterioration
of the uniformity after puncture repair (that is, the uniformity of
the weight including the pneumatic tire, the noise damper, and the
puncture repair liquid), thereby, it is possible that the running
noise is effectively suppressed.
[0017] Further, the water absorption rate of the first part is set
to the above-mentioned lower limit value. Therefore, it is possible
that the first part absorbs the puncture repair liquid necessary
for filling a puncture hole formed on the outer side in the tire
radial direction of the noise damper, thereby, the puncture repair
is not obstructed.
[0018] Furthermore, the air permeability of the second part
measured in accordance with Japanese Industrial standard JIS-L1096
is in a range of from 1 to 7 cm3/cm2/s. Therefore, the second part
can minimize the absorption of the puncture repair liquid while
decreasing the running noise of the pneumatic tire. Thereby, the
pneumatic tire according to the present invention can prevent the
deterioration of the uniformity after puncture repair while
suppressing the running noise.
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 illustrating a state in which
the tire having a puncture hole is repaired.
[0021] FIG. 3 a cross-sectional view of a pneumatic tire as another
embodiment of the present invention.
[0022] FIG. 4 a cross-sectional view of a pneumatic tire as yet
another embodiment of the present invention.
DESCRIPTION OF THE REFERENCE SIGNS
[0023] 1 pneumatic tire [0024] 16 tire inner cavity surface [0025]
17 tire inner cavity [0026] 20 noise damper [0027] 23 first part
[0028] 24 second part
BEST MODE FOR CARRYING OUT THE INVENTION
[0029] An embodiment of the present invention will now be described
in conjunction with accompanying drawings.
[0030] FIG. 1 is a tire meridian section passing through a tire
rotational axis of a pneumatic tire (hereinafter may be simply
referred to as "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.
[0031] 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.
[0032] 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.
[0033] As shown in FIG. 1, the tire 1 is suitably used as a radial
tire for passenger cars, for example. The tire 1 in this embodiment
has a carcass 6, a belt layer 7, a band layer 9, an inner liner 10,
and a noise damper 20. Further, the tire 1 in this embodiment has a
damping rubber body 30.
[0034] The carcass 6 extends between a pair of bead portions 4, 4.
The carcass 6 is formed of at least one, one in this embodiment,
carcass ply 6A. The carcass ply 6A includes a main body portion 6a
extending between bead cores 5 of the bead portions 4 via a tread
portion 2 and sidewall portions 3 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. Between the main body
portion 6a and each of the turned up portions 6b of the carcass ply
6A, a bead apex rubber 8 extending outwardly in a tire radial
direction from respective one of the bead cores 5.
[0035] Carcass cords (not shown) are arranged at an angle in a
range of from 80 to 90 degrees with respect to a tire equator C in
the carcass ply 6A, for example. As the carcass cords, organic
fiber cords such as aromatic polyamide and rayon can be used, for
example.
[0036] A tread rubber 11 disposed in the tread portion 2, sidewall
rubbers 12 each forming an outer surface of respective one of the
sidewall portions 3, bead rubbers 13 each forming an outer surface
of respective one of the bead portions 4, and the like are arranged
outside the carcass 6. The tread rubber 11 is provided with grooves
14 each recessed inwardly in the tire radial direction from a
ground contacting surface thereof.
[0037] The belt layer 7 is arranged on an outer side in the tire
radial direction of the carcass 6 and inside the tread portion 2.
The belt layer 7 is formed of two belt plies, i.e. radially inner
and outer belt plies 7A and 7B. The belt plies 7A and 7B are
provided with belt cords (not shown) arranged at an angle in a
range of from 10 to 35 degrees with respect to a tire
circumferential direction, for example. The belt plies 7A and 7B
are overlapped so that the belt cords of the belt ply 7A and the
belt cords of the belt ply 7B cross each other. As the belt cords,
steel, aramid, rayon or the like can be used, for example.
[0038] The band layer 9 is arranged on an outer side the tire
radial direction of the belt layer 7. The band layer 9 in this
embodiment includes a band ply 9A in which band cords are wound in
a spiral manner at an angle not more than 10 degrees, preferably
not more than 5 degrees with respect to the tire circumferential
direction. As the band cords, an organic fiber cord such as a nylon
cord can be used, for example.
[0039] The inner liner 10 is arranged on an inner side in the tire
radial direction of the carcass 6. The inner liner 10 forms a tire
inner cavity surface 16. The inner liner 10 is made of
air-impermeable butyl-type rubber, for example.
[0040] The noise damper 20 is formed of a porous material having a
large number of pores on a surface thereof. The noise damper 20 is
fixed to the tire inner cavity surface 16 of the tread portion 2.
The noise damper 20 in this embodiment has an elongated belt-like
shape having a bottom surface fixed to the tire inner cavity
surface 16 and extends in the tire circumferential direction. Outer
end portions in the circumferential direction of the noise damper
20 are in contact with each other to form a substantially annular
shape. Note that the outer end portions of the noise damper 20 may
be spaced apart in the tire circumferential direction.
[0041] As the porous material, a porous sponge material is
exemplified, for example. The sponge material is a cavernous porous
structure body. The sponge material includes 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. The "porous structure body" includes not
only a body having the interconnected cells but also a body having
closed cells.
[0042] The noise damper 20 in this embodiment 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, the
cross-sectional shape is formed as a flat and horizontally
elongated shape in which a height is smaller than a width in the
tire axial direction.
[0043] In the noise damper 20 configured as such, the pores on the
surface of or inside the noise damper convert vibration energy of
the vibrating air into thermal energy, therefore, it is possible
that the vibration energy is consumed. Thereby, sound (cavity
resonance energy) is decreased, therefore, it is possible that the
running noise (around 250 Hz, for example) is decreased. The sponge
material is easy to deform such as contraction, flexion, etc.
Thereby, the noise damper 20 can deform flexibly following the
deformation of the inner liner 10 during running.
[0044] In order to effectively suppress the cavity resonance in a
tire inner cavity 17, it is preferred that total 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 17. The total 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
approximately obtained by the following formula (2) in the standard
state:
V2=A.times.{(Di-Dr)/2+Dr}.times..pi. (2)
wherein
[0045] A: a cross-sectional area of the tire inner cavity obtained
by CT scanning the tire-rim assembly
[0046] Di: a maximum outer diameter of the tire inner cavity
surface
[0047] Dr: rim diameter
[0048] .pi.: circumference ratio
[0049] When the total volume V1 of the noise damper 20 is less than
0.4% of the total volume V2 of the tire inner cavity 17, it is
possible that the noise damper 20 cannot sufficiently convert the
vibration energy of the air into thermal energy. On the other hand,
if the total volume V1 is more than 30% of the total volume V2, it
is possible that mass and production cost of the tire 1 are
increased.
[0050] 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 durability
of the noise damper 20 is deteriorated. Conversely, 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, for example, the noise
damper 20 may be pulled by the foreign object, therefore, it is
possible that the noise damper 20 comes off the tire inner cavity
surface 16 of the tread portion 2.
[0051] The noise damper 20 is configured to include a first part 23
arranged on an outer side in the tire radial direction and a second
part 24 arranged on an inner side in the tire radial direction of
the first part. In this embodiment, the first part 23 and the
second part 24 are exposed in the tire inner cavity 17. In this
embodiment, the porous material forming the first part 23 is
different from the porous material forming the second part 24. The
first part 23 and the second part 24 are fixed by an adhesive or
thermal welding or the like, for example.
[0052] The first part 23 in this embodiment has a laterally
elongated rectangular cross-sectional shape. An outer peripheral
surface in the tire radial direction of the first part 23 is fixed
to the tire inner cavity surface 16. A thickness T3 of the first
part 23 is set to be in about a range of from 10% to 30% of a
maximum thickness T2 (not shown) of the tread portion 2, for
example.
[0053] A width in the tire axial direction of the second part 24 in
this embodiment decreases from the first part 23 toward a tire
radial direction so as to have a trapezoidal cross section. An
outer peripheral surface in the tire radial direction of the second
part 24 is fixed to an inner peripheral surface in the tire radial
direction of the first part 23.
[0054] At least one second part 24, two second parts 24 in this
embodiment, are provided. These second parts 24, 24 are provided
spaced apart from each other on both sides in the tire axial
direction with the tire equator C therebetween. Thereby, a concave
groove 21 extending continuously in the circumferential direction
is provided on a side of the inner surface in the tire radial
direction of the noise damper 20. The noise damper 20 having the
concave groove 21 configured as such can increase a contact area of
the tire inner cavity 17 with the air, therefore, it is possible
that the cavity resonance in the tire inner cavity 17 is
effectively suppress. A thickness T4 of each of the second parts 24
is set to be in about a range of from 40% to 70% of the maximum
thickness T2 (not shown) of the tread portion 2, for example. A
width W4 of each of the second parts 24 is set to be in about a
range of from 20% to 45% of a width W3 of the first part 23, for
example.
[0055] Density of each of the second parts 24 in this embodiment is
set to be larger than density of the first part 23. Thereby, it is
possible that the cavity resonance is effectively suppressed in the
tire inner cavity 17 at the second parts 24, which are in contact
with the air in the tire inner cavity 17 more than the first part
23.
[0056] In order to effectively exert such an effect, it is
preferred that the density of each of the second parts 24 is set to
be in a range of from 1.1 to 2.3 times the density of the first
part 23. Note that if the density of each of the second parts 24 is
less than 1.1 times the density of the first part 23, it is
possible that the cavity resonance in the tire inner cavity 17 is
not sufficiently suppressed. Conversely, if the density of each of
the second parts 24 is more than 2.3 times the density of the first
part 23, a difference in the density between the first part 23 and
each of the second parts 24 is increased, therefore, it is likely
that a part around the boundary between the first part 23 and each
of the second parts 24 is damaged. From this point of view, the
density of each of the second part 24 is preferably not less than
1.3 times and preferably not more than 2.0 times the density of the
first part 23.
[0057] The density of the second part 24 can be appropriately set
as long as the above relation is satisfied. Note that if the
density of each of the second parts 24 is small, it is possible
that the cavity resonance in the tire inner cavity 17 is not
sufficiently suppressed. Conversely, even if the density of each of
the second parts 24 is large, it is possible that the mass of tire
1 is increased. From this point of view, the density of each of the
second parts 24 is preferably not less than 20 kg/m3, more
preferably not less than 23 kg/m3, and preferably not more than 35
kg/m3, more preferably not more than 32 kg/m3.
[0058] Further, the density of the first part 23 can be
appropriately set as long as the above relation is satisfied. Note
that if the density of the first part 23 is small, it is possible
that the cavity resonance in the tire inner cavity 17 is not
sufficiently suppressed. Conversely, even if the density of the
first part 23 is large, it is possible that the mass of the tire 1
is increased. From this point of view, the density of the first
part 23 is preferably not less than 15 kg/m3, more preferably not
less than 18 kg/m3, and preferably not more than 30 kg/m3, more
preferably not more than 27 kg/m3.
[0059] FIG. 2 is a cross-sectional view illustrating a state in
which the tire 1 having a puncture hole 26 is repaired. For the
puncture repair of the tire 1 having the noise damper 20, puncture
repair liquid 27 for sealing the puncture hole 26 is used, for
example. In FIG. 2, the puncture hole 26 is formed on the outer
side in the tire radial direction of the noise damper 20. When the
puncture repair liquid 27 is injected in the tire inner cavity, the
puncture repair liquid 27 is absorbed by the first part 23 and gets
into the puncture hole 26. Thereby, it is possible that the
puncture repair liquid 27 seals the puncture hole 26.
[0060] Note that if a water absorption rate of the first part 23 is
large, the puncture repair liquid 27 is absorbed more than
necessary by the first part 23. Thereby, even if the tire 1 is
rotated after the injection of the puncture repair liquid, the
puncture repair liquid 27 is not uniformly distributed in the tire
circumferential direction. Therefore, it is possible that the
uniformity of the tire 1 is likely to be deteriorated. The term
uniformity as used herein refers to the uniformity of the weight
including the pneumatic tire 1, the noise damper 20, and the
puncture repair liquid 27. If such uniformity is impaired, it is
possible that the running noise tends to be large.
[0061] In this embodiment, the water absorption rate of the first
part 23 calculated by a formula (1) shown below is limited to be in
a range of from 5% to 25%. Note that in the following formula (1),
"weight change before and after immersion" is a weight increase of
a test piece having a length of 50 mm, a width of 50 mm, and a
thickness of 20 mm when it is compressed in the thickness direction
at a compression ratio of 50%, and then immersed in water at a
temperature of 20 degrees Celsius and at water depth of 10 cm for
24 hours.
Water absorption rate (%)=Weight change before and after immersion
(g)/Volume at 50% compression(cm3).times.100 (1)
[0062] The water absorption rate of the first part 23 is smaller
than the water absorption rate of the repair liquid permeable layer
of the above-mentioned Patent Literature 1 (about 30%, for
example). The water absorption rate can be set by adjusting a water
repellent agent or a hydrophilic agent added to the porous
material, for example.
[0063] Owing to the water absorption rate, it is possible that the
first part 23 prevents the puncture repair liquid 27 from being
absorbed more than necessary. Therefore, in the tire 1 in this
embodiment, it is possible that the puncture repair liquid 27 is
uniformly distributed in the tire circumferential direction by the
rotation of the tire after the injection of the puncture repair
liquid as compared with a tire (not shown) with the first portion
having a large water absorption rate, for example. Therefore, the
tire 1 in this invention can prevent deterioration of the
uniformity after puncture repair (that is, the uniformity of the
weight including the tire 1, the noise damper 20, and the puncture
repair liquid 27), thereby, it is possible that the running noise
is effectively suppressed.
[0064] The water absorption rate of the first part 23 is set to the
above-mentioned lower limit value. Therefore, it is possible that
the first part 23 absorbs the puncture repair liquid 27 necessary
for filling the puncture hole 26 formed on the outer side in the
tire radial direction of the noise damper 20. Thereby, the first
part 23 does not obstruct the puncture repair.
[0065] Note that if the water absorption rate of the first part 23
is more than 25%, the puncture repair liquid 27 is absorbed more
than necessary in the first part 23, therefore, it is possible that
the uniformity of the tire 1 is deteriorated. Conversely, if the
water absorption rate of the first part 23 is less than 5%, it is
possible that the puncture repair liquid 27 necessary for filling
the puncture hole 26 is not absorbed at an early stage. From this
point of view, the absorption rate of the first part 23 is
preferably not more than 20%, and preferably not less than 10%.
[0066] Of the first part 23 and the second part 24, most of the
puncture repair liquid 27 is absorbed in the first part 23.
Therefore, it is possible that the water absorption rate of the
second part 24 is appropriately set. Note that if the water
absorption rate of the second part 24 is large, it is possible that
the puncture repair liquid 27 is absorbed more than necessary by
the second part 24. Conversely, if the water absorption rate of the
second part 24 is small, it is possible that the effect of
suppressing the cavity resonance is decreased. Thereby, it is
preferred that the water absorption rate of the second part 24 is
set to be in a range of from 1% to 5%.
[0067] In this embodiment, air permeability of the second part 24
measured in accordance with Japanese Industrial standard JIS-L1096
is set larger than the air permeability of the first part 23. The
second part 24 configured as such can effectively decrease the
cavity resonance in the tire inner cavity 17. Note that a method of
adjusting the air permeability of the second part 24 is not
particularly limited. The air permeability of the second part 24
can be decreased by increasing viscosity of the raw material of the
second part 24 and making the cells finer, for example. On the
other hand, the air permeability of the second part 24 can be
increased by decreasing the viscosity of the raw material of the
second part 24 and making the cells larger.
[0068] In order to effectively exert such an effect, it is
preferred that the air permeability of the second part 24 is set to
be in a range of from 1 to 7 cm3/cm2/s. Note that if the air
permeability of the second part 24 is less than 1 cm3/cm2/s, it is
possible that the cavity resonance in the tire inner cavity 17 is
not sufficiently suppressed. Conversely, if the air permeability of
the second part 24 is more than 7 cm3/cm2/s, it is possible that
the second part 24 absorbs the puncture repair liquid 27 more than
necessary. From this point of view, the air permeability of the
second part 24 is preferably not less than 2 cm3/cm2/s, and
preferably not more than 6 cm3/cm2/s.
[0069] As described above, in the tire 1 in this embodiment, by
limiting the water absorption rate of the first part 23 and the air
permeability of the second part 24 to the above ranges, it is
possible that deterioration of the uniformity after puncture repair
is effectively prevented while the running noise being
suppressed.
[0070] As shown in FIG. 1, the damping rubber body 30 in this
embodiment is disposed inside the tread portion 2. The damping
rubber body 30 is arranged on an inner side in the tire radial
direction or on an outer side in the tire radial direction of the
belt layer 7 (in this embodiment, on the inner side in the tire
radial direction of the belt layer 7). The damping rubber body 30
in this embodiment is disposed between the carcass 6 and the belt
layer 7. The damping rubber body 30 is made of rubber different
from topping rubber (not shown) included in the carcass ply 6A and
the belt ply 7A.
[0071] In this embodiment, hardness H1 of the damping rubber body
30 is set smaller than hardness H2 of the tread rubber 11 arranged
in the tread portion 2. 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.
[0072] The damping rubber body 30 configured as such can
effectively suppress vibration of the tread portion 2, therefore,
it is possible that the running noise (around 160 Hz, for example)
is effectively decreased. Besides, the noise damper 20 described
above can also decrease the running noise around 250 Hz, therefore,
it is possible that noise performance of the tire 1 is effectively
improved. Further, the damping rubber body 30 in this embodiment is
disposed between the carcass 6 and the belt layer 7, therefore,
vibration of the carcass 6 and the belt layer 7 is suppressed,
thereby, it is possible that road noise is decreased.
[0073] In order to effectively exert such an effect, it is
preferred that a ratio (H1/H2) of the hardness H1 of the damping
rubber body 30 and the hardness H2 of the tread rubber 11 is set to
be in a range of from 0.5 to 1.0, that is not less than 0.5 and
less than 1.0. Note that if the ratio (H1/H2) is not less than 1.0,
it is possible that the vibration of the tread portion 2 cannot be
sufficiently suppressed. Conversely, if the ratio (H1/H2) is less
than 0.5, rigidity of the damping rubber body 30 becomes small,
therefore, it is possible that steering stability is not
maintained. From this point of view, the ratio (H1/H2) is
preferably not more than 0.8, and preferably not less than 0.6.
[0074] The hardness H1 of the damping rubber body 30 and the
hardness H2 of the tread rubber 11 can be appropriately set as long
as the ratio (H1/H2) satisfies the above conditions. It is
preferred that the hardness H1 in this embodiment is set to be in a
range of from 30 to 73 degrees. On the other hand, it is preferred
that the hardness H2 in this embodiment is set to be in a range of
from 55 to 75 degrees. Thereby, the tire 1 can effectively suppress
the vibration of the tread portion 2 while maintaining the steering
stability.
[0075] Note that rubber specialized for adhesion performance of the
carcass cords (not shown) and the belt cords (not shown) (that is,
rubber with low hardness) is used for the topping rubber (not
shown) included in the carcass ply 6A and the belt ply 7A.
Therefore, it is preferred that the hardness H1 of the damping
rubber body 30 is larger than hardness H3 of the topping rubber.
Note that a ratio (H1/H3) of the hardness H1 of the damping rubber
body 30 and the hardness H3 of the topping rubber can be set to be
in a range of from 0.4 to 1.2.
[0076] A width W1 in the tire axial direction of the damping rubber
body 30 can be appropriately set. The width W1 of the damping
rubber body 30 in this embodiment is set to be in a range of from
60% to 130% of a width W2 in the tire axial direction of the belt
layer 7. The damping rubber body 30 configured as such can
effectively suppress the vibration of the tread portion 2 while
preventing an increase in the mass of the tire 1.
[0077] Note that if the width W1 of the damping rubber body 30 is
less than 60% of the width W2 of the belt layer 7, it is possible
that the vibration of the tread portion 2 cannot be sufficiently
suppressed. Conversely, if the width W1 of the damping rubber body
30 is more than 130% of the width W2 of the belt layer 7, it is
possible that the increase of the mass of the tire 1 cannot be
prevented. From this point of view, it is preferred that the width
W1 of the damping rubber body 30 is not less than 70% and not more
than 120% of the width W2 of the belt layer 7.
[0078] Positions of each of outer ends 30t in the tire axial
direction of the damping rubber body 30 are appropriately set. Each
of the outer end 30t in this embodiment terminates axially outside
with respect to respective one of outer ends 7t in the tire axial
direction of the belt layer 7. Further, each of the outer ends 30t
terminates axially inside with respect to respective one of outer
ends 9t in the tire axial direction of the band layer 9. Thereby,
the damping rubber body 30 can cover the entire area in the tire
axial direction of the belt layer 7 on the radially inner side,
therefore, it is possible that the running noise (around 160 Hz,
for example) is effectively decreased.
[0079] A maximum thickness T1 of the damping rubber body 30 can be
appropriately set. Note that if the maximum thickness T1 is small,
it is possible that the vibration of the tread portion 2 cannot be
sufficiently suppressed. Conversely, if the maximum thickness T1 is
large, the movement of the tread portion 2 becomes large,
therefore, it is possible that the steering stability is
deteriorated. From such a point of view, it is preferred that the
maximum thickness T1 is not less than 4% and not more than 20% of
the maximum thickness T2 (not shown) of the tread portion 2.
[0080] It is preferred that a loss tangent tan .delta. at 0 degrees
Celsius of the tread rubber 11 is not less than 0.40. Thereby, wet
grip performance of the tire 1 is improved. Such an increase in the
wet grip performance can be devoted to the decrease of volume of
the grooves 14 of the tread portion 2, for example, therefore, it
is possible that the running noise is further decreased.
[0081] Further, it is preferred that the loss tangent tan .delta.
at 70 degrees Celsius of the tread rubber 11 is not more than 0.20.
Thereby, rolling resistance of the tire 1 can be decreased and
deterioration of fuel efficiency can be suppressed by providing the
noise damper 20 and the damping rubber body 30.
[0082] The loss tangent tan .delta. at 0 degrees Celsius and the
loss tangent tan .delta. at 70 degrees Celsius are measured in
accordance with Japanese Industrial standard JIS-K6394. The loss
tangent tan .delta. at 0 degrees Celsius and the loss tangent tan
.delta. at 70 degrees Celsius in this embodiment are measured 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%.
[0083] The tread rubber 11 in this embodiment contains carbon
black, silica, and sulfur. A content A1 (phr) of the carbon black,
a content A2 (phr) of the silica, and a content A3 (phr) of the
sulfur can be set as appropriate but it is preferred that they
satisfy the relationship of the following formula (1):
(1.4.times.A1+A2)/A3.gtoreq.20 (1).
[0084] By satisfying the above formula (1), the ratio of the carbon
black content A1 and the silica content A2 in the tread rubber 11
can be increased, therefore, anti-wear performance is improved. It
is possible that the running noise is further decrease by devoting
this increase in the anti-wear performance to decrease in the
volume of the grooves 14 of the tread portion 2, for example.
Furthermore, when the puncture repair is performed by using the
puncture repair liquid, occurrence of uneven wear of the tread
rubber 11 is suppressed even when the puncture repair liquid is
unevenly distributed.
[0085] Although the damping rubber body 30 in this embodiment is
arranged on the inner side in the tire radial direction of the belt
layer 7, it is not limited to such an embodiment. The damping
rubber body 30 may be arranged on the outer side in the tire radial
direction of the belt layer 7. FIG. 3 is a tire meridian section
passing through the tire rotational axis of the tire 1, in the
standard state, according to another embodiment of the present
invention. Note that, in this embodiment, the same components as
those of the previous embodiment are denoted by the same reference
numerals, and the description thereof may be omitted.
[0086] A damping rubber body 40 in this embodiment is disposed
between the belt layer 7 and the band layer 9. The damping rubber
body 40 configured as such can effectively suppress the vibration
of the tread portion 2, therefore, it is possible that the running
noise (around 160 Hz for example) is effectively decreased.
Moreover, the damping rubber body 40 in this embodiment is disposed
between the belt layer 7 and the band layer 9, therefore, the
vibration of the belt layer 7 and the band layer 9 is suppressed,
thereby, it is possible that the road noise is decreased.
[0087] Outer ends 40t in the tire axial direction of the damping
rubber body 40 in this embodiment can be appropriately set. Each of
the outer ends 40t in this embodiment terminates axially outside
with respect to respective one of the outer ends 7t of the belt
layer 7. Further, each of the outer ends 40t terminates axially
inside with respect to respective one of the outer ends 9t of the
band layer 9. Thereby, the damping rubber body 40 can cover the
entire area in the tire axial direction of the belt layer 7 on the
radially outer side, therefore, it is possible that the running
noise (around 160 Hz, for example) is effectively decreased.
[0088] FIG. 4 is a tire meridian section passing through the tire
rotational axis of the tire 1, in the standard state, according to
yet another embodiment of the present invention. Note that, in this
embodiment, the same components as those of the previous
embodiments are denoted by the same reference numerals, and the
description thereof may be omitted.
[0089] A damping rubber body 50 in this embodiment is arranged on
the outer side in the tire radial direction of the band layer 9.
The damping rubber body 50 configured as such can effectively
suppress the vibration of the tread portion 2, therefore, it is
possible that the running noise (around 160 Hz for example) is
effectively decreased. Moreover, the damping rubber body 50 in this
embodiment is arranged on the outer side in the tire radial
direction of the band layer 9, therefore, the vibration of the band
layer 9 is suppressed, thereby, it is possible that the road noise
is decreased.
[0090] Outer ends 50t in the tire axial direction of the damping
rubber body 50 in this embodiment can be appropriately set. Each of
the outer ends 50t in this embodiment terminates axially outside
with respect to respective one of the outer ends 7t of the belt
layer 7. Further, each of the outer ends 50t terminates axially
inside with respect to respective one of the outer ends 9t of the
band layer 9. Thereby, the damping rubber body 50 can cover the
entire area in the tire axial direction of the belt layer 7 on the
radially outer side, therefore, it is possible that the running
noise (around 160 Hz, for example) is effectively decreased.
[0091] While detailed description has been made of the especially
preferred embodiments of the present invention, the present
invention can be embodied in various forms without being limited to
the illustrated embodiments. For example, the embodiments in which
the porous material constituting the first part 23 is different
from the porous material of the second part 24 have been described
above as examples, but the second part 24 may be formed of the same
porous material as the first part 23. In this case, the first part
23 and the second part 24 may be integrally formed.
WORKING EXAMPLES
Working Examples A
[0092] Tires having the basic structure shown in FIG. 1 and the
noise damper of Table 1 were manufactured, and then their
performance was evaluated (Examples 1 to 26). For comparison, a
tire having no noise damper and damping rubber body (Reference 1),
tires in which the water absorption rate of the first portion is
out of the range of from 5% to 25% (References 2 and 3) were
manufactured, and then their performance was evaluated. Further,
tires in which the air permeability of the second part is out of
the range of from 1 to 7 cm3/cm2/s (References 4 and 5) were
manufactured, and then their performance was evaluated. The
specifications common to each of the Examples and the References
are as follows.
[0093] Tire size: 165/65R18
[0094] Rim size: 18.times.7JJ
[0095] Inner pressure: 320 kPa
[0096] Test car: domestically produced FR car with displacement of
2500 cc
[0097] Composition of Tread rubber:
[0098] Natural rubber (TSR20): 15 phr
[0099] SBR1 (terminal modified): 45 phr (amount of bound styrene:
28%, vinyl group content: 60%,
[0100] glass transition point: -25 degrees Celsius)
[0101] SBR2 (terminal modified): 25 phr (amount of bound styrene:
35%, vinyl group content: 45%,
[0102] glass transition point: -25 degrees Celsius)
[0103] BR (BR150B): 15 phr
[0104] Silane coupling agent (Si266): 4 phr
[0105] Resin (SYLVARES SA85 available from Arizona Chemical co.): 8
phr
[0106] Oil: 4 phr
[0107] Wax: 1.5 phr
[0108] Age resistor (6C): 3 phr
[0109] Stearic acid: 3 phr
[0110] Zinc oxide: 2 phr
[0111] Vulcanization accelerator (NS): 2 phr
[0112] Vulcanization accelerator (DPG): 2 phr
[0113] Carbon black (N220): 5 phr
[0114] Silica (VN3, 1115MP): 70 phr
[0115] Sulfur: 2 phr
[0116] Hardness H2 of tread rubber of vulcanized tire: 64
degrees
[0117] Maximum thickness T2: 10 mm
[0118] Loss tangent tan .delta. at 0 degrees Celsius: 0.50
[0119] Loss tangent tan .delta. at 70 degrees Celsius: 0.10
[0120] (1.4.times.carbon black content A+silica content B)/sulfur
content C: 15.0
[0121] Axial width W2 of belt layer: 120 mm
[0122] Hardness H3 of topping rubber of carcass ply and belt ply:
60 degrees
[0123] Composition of damping rubber body:
[0124] Natural rubber (TSR20): 65 phr
[0125] SBR (Nipol 1502): 35 phr
[0126] Carbon black N220: 52 phr
[0127] Oil: 15 phr
[0128] Stearic acid: 1.5 phr
[0129] Zinc oxide: 2 phr
[0130] Sulfur: 3 phr
[0131] Vulcanization accelerator (CZ): 1 phr
[0132] Hardness H1 of tread rubber of vulcanized tire: 58
degrees
[0133] Maximum thickness T1 of damping rubber body: 1 mm
[0134] Ratio (H1/H2) of Hardness H1 of damping rubber body and
Hardness H2 of tread rubber: 0.7
[0135] Ratio (W1/W2) of width W1 of damping rubber body and width
W2 of belt layer: 100%
Test methods are as follows.
<Noise Performance>
[0136] Each of the test tires was mounted on the above rim and was
mounted on all wheels of the above test car under the above
condition of the inner pressure. Then a total sound pressure
(decibel) of the running noise (in a range of from 100 to 200 Hz
and in a range of from 200 to 300 Hz) was measured by using a sound
concentrating microphone attached to the center part of the
backrest of the driver's seat while the test car was driven on a
road for measuring road noise (rough asphalt surface road) at a
speed of 60 km/h. The results are indicated by an index based on
the Example 2 being 100, wherein the larger the numerical value,
the smaller the running noise is, which is better.
<Uniformity after Puncture Repair>
[0137] Before injecting the above puncture repair liquid, a dynamic
imbalance amount of each of the test tires was measured by using a
tire balancer. Next, 500 ml of the puncture repair liquid was
injected, each of the test tires was inflated with air to 300 kPa,
and after 1 minute of rotation, the dynamic imbalance amount of
each of the test tires was measured. A change rate of the dynamic
imbalance amount was obtained by dividing the dynamic imbalance
amount after the injection of the puncture repair liquid by the
dynamic imbalance amount before the injection of the puncture
repair liquid. The evaluation was indicated by an index based on a
reciprocal of the change rate of the dynamic imbalance amount of
the Example 2 being 100, wherein a larger numerical value is
better.
<Easiness of Puncture Repair>
[0138] Each of the test tires was mounted on the above rim and
punctured by rolling on a nail. Then, each of the test tires was
repaired with the puncture repair liquid (main ingredient: rubber
latex), and the time required for the repair was measured. The
results are indicated by an index based on the Example 2 being 100,
wherein the larger the numerical value, the shorter the repair
time, which means that the puncture repair is easier.
<Separation Resistance Performance of Noise Damper when Nail
Sticks>
[0139] Each of the test tires was mounted on the above rim and
mounted on all wheels of the above test car under the condition of
the above inner pressure. And each of the test tires was punctured
by rolling on a nail, then the damaged part was disassembled to
measure the area of separation of the noise damper from the tire
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 2 being 100, wherein the larger the numerical
value, the higher the separation resistance performance is, which
is better.
<Tire Mass>
[0140] The mass per tire was measured for each of the test tires.
The results are indicated by an index based on the reciprocal of
the mass of the tire of the Example 2 being 100, wherein the larger
the numerical value, the lighter the tire is.
<Durability of Noise Damper>
[0141] Each of the test tires was mounted on the above rim and
inflated to the above inner pressure. 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 tire load of 4.8
kN and the speed of 80 km/h. The results are indicated by an index
based on the Example 2 being 100, wherein the larger the numerical
value, the higher the durability is, which is better.
[0142] The test results are shown in Table 1.
TABLE-US-00001 TABLE 1 Ref. 1 Ref. 2 Ex. 1 Ex. 2 Ex. 3 Ref. 3 Ref.
4 Ex. 4 Ex. 5 Ref. 5 Ex. 6 Ex. 7 Ex. 8 Presence (P) or A P P P P P
P P P P P P P Absence (A) of Noise clamper Presence (P) or A P P P
P P P P P P P P P Absence (A) of Damping rubber body Water
absorption [%] -- 3.0 5.0 15.0 25.0 30.0 15.0 15.0 15.0 15.0 15.0
15.0 15.0 rate of First part Air permeability [cm3/ -- 4.0 4.0 4.0
4.0 4.0 0.5 1.0 7.0 8.0 4.0 4.0 4.0 of Second part cm2/s] Density
of First [kg/m3] -- 22.0 22.0 22.0 22.0 22.0 22.0 22.0 22.0 22.0
22.0 22.0 22.0 part Density of Second [kg/m3] -- 27.0 27.0 27.0
27.0 27.0 27.0 27.0 27.0 27.0 52.8 50.6 39.6 part Density of Second
-- 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 2.4 2.3 1.8 part/Density of
First part Ratio (V1/V2) of [%] -- 15.0 15.0 15.0 15.0 15.0 15.0
15.0 15.0 15.0 15.0 15.0 15.0 volume V1 of Noise damper and Total
volume V2 of Tire inner cavity Tensile strength [kPa] -- 90.0 90.0
90.0 90.0 90.0 90.0 90.0 90.0 90.0 90.0 90.0 90.0 of Noise damper
Noise performance [index] 80 100 100 100 100 100 90 98 104 106 109
106 103 [larger is better] Uniformity after [index] -- 103 102 100
96 90 103 102 96 92 100 100 100 puncture repair [larger is better]
Easiness of [index] 110 90 98 100 106 109 100 100 100 100 100 100
100 puncture repair [larger is better] Separation [index] -- 100
100 100 100 100 100 100 100 100 100 100 100 resistance [larger
performance of is better] Noise damper when Nail sticks Tire mass
[index] 115 100 100 100 100 100 100 100 100 100 94 96 98 [larger is
better] Durability of [index] 100 100 100 100 100 100 100 100 100
100 97 98 100 Noise damper [larger is better] Ex. 9 Ex. 10 Ex. 11
Ex. 12 Ex. 13 Ex. 14 Ex. 15 Presence (P) or P P P P P P P Absence
(A) of Noise clamper Presence (P) or P P P P P P P Absence (A) of
Damping rubber body Water absorption [%] 15.0 15.0 15.0 15.0 15.0
15.0 15.0 rate of First part Air permeability [cm3/cm2/s] 4.0 4.0
4.0 4.0 4.0 4.0 4.0 of Second part Density of First [kg/m3] 22.0
22.0 12.0 15.0 30.0 32.0 22.0 part Density of Second [kg/m3] 24.2
22.0 27.0 27.0 27.0 27.0 18.0 part Density of Second 1.1 1.0 2.3
1.8 0.9 0.8 0.8 part/Density of First part Ratio (V1/V2) of [%]
15.0 15.0 15.0 15.0 15.0 15.0 15.0 volume V1 of Noise damper and
Total volume V2 of Tire inner cavity Tensile strength [kPa] 90.0
90.0 90.0 90.0 90.0 90 90 of Noise damper Noise [index] 99 98 96 98
102 104 96 performance [larger is better] Uniformity [index] 100
100 100 100 100 100 100 after puncture [larger repair is better]
Easiness of [index] 100 100 100 100 100 100 100 puncture repair
[larger is better] Separation [index] 100 100 100 100 100 100 100
resistance [larger performance of is better] Noise damper when Nail
sticks Tire mass [index] 101 102 104 102 98 96 104 [larger is
better] Durability of [index] 101 104 100 100 100 100 100 Noise
damper [larger is better] Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21
Presence (P) or P P P P P P Absence (A) of Noise clamper Presence
(P) or P P P P P P Absence (A) of Damping rubber body Water
absorption [%] 15.0 15.0 15.0 15.0 15.0 15.0 rate of First part Air
permeability [cm3/cm2/s] 4.0 4.0 4.0 4.0 4.0 4.0 of Second part
Density of First [kg/m3] 22.0 22.0 22.0 22.0 22.0 22.0 part Density
of Second [kg/m3] 20.0 35.0 37.0 27.0 27.0 27.0 part Density of
Second 0.9 1.6 1.7 1.2 1.2 1.2 part/Density of First part Ratio
(V1/V2) of [%] 15.0 15.0 15.0 0.3 0.4 30.0 volume V1 of Noise
damper and Total volume V2 of Tire inner cavity Tensile strength
[kPa] 90 90 90 90 90 90 of Noise damper Noise [index] 98 103 106 95
96 105 performance [larger is better] Uniformity [index] 100 100
100 100 100 100 after puncture [larger repair is better] Easiness
of [index] 100 100 100 100 100 100 puncture repair [larger is
better] Separation [index] 100 100 100 100 100 100 resistance
[larger performance of is better] Noise damper when Nail sticks
Tire mass [index] 102 98 96 110 105 95 [larger is better]
Durability of [index] 100 100 100 100 100 100 Noise damper [larger
is better] Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Presence (P) or
Absence P P P P P (A) of Noise clamper Presence (P) or Absence P P
P P P (A) of Damping rubber body Water absorption rate [%] 15.0
15.0 15.0 15.0 15.0 of First part Air permeability of [cm3/cm2/s]
4.0 4.0 4.0 4.0 4.0 Second part Density of First part [kg/m3] 22.0
22.0 22.0 22.0 22.0 Density of Second part [kg/m3] 27.0 27.0 27.0
27.0 27.0 Density of Second part/ 1.2 1.2 1.2 1.2 1.2 Density of
First part Ratio (V1/V2) of volume [%] 35.0 15.0 15.0 15.0 15.0 V1
of Noise damper and Total volume V2 of Tire inner cavity Tensile
strength of [kPa] 90 60 70 115 125 Noise damper Noise performance
[index] 110 100 100 100 100 [larger is better] Uniformity after
[index] 100 100 100 100 100 puncture repair [larger is better]
Easiness of [index] 100 100 100 100 100 puncture repair [larger is
better] Separation [index] 100 103 102 98 96 resistance [larger
performance of is better] Noise damper when Nail sticks Tire mass
[index] 90 100 100 100 100 [larger is better] Durability of [index]
100 97 98 102 104 Noise damper [larger is better]
[0143] From the test results, the tires as the Examples could
prevent the deterioration of the uniformity after the puncture
repair while suppressing the running noise as compared with the
tires as the References. Further, the tires as the Examples showed
better easiness of puncture repair as compared with the tires as
the Reference 2.
Working Examples B
[0144] Tires having the basic structure shown in FIG. 1, 2 or 3 and
the noise damper and the damping rubber body of Table 2 were
manufactured, and then their performance was evaluated (Examples 27
to 39). The specifications common to each of the Examples are the
same as those of the working Examples A except for those listed in
Table 2 and shown below.
[0145] First part of noise damper: [0146] Water absorption rate:
15.0(%) [0147] Density: 22.0 (kg/m3)
[0148] Second part of noise damper: [0149] Air permeability: 4.0
(cm3/cm2/s) [0150] Density: 27.0 (kg/m3)
[0151] Tensile strength of noise damper: 90.0 (kPa)
[0152] Ratio (V1/V2) of total volume V1 of noise damper and total
volume V2 of tire inner cavity: 15(%)
[0153] Hardness H1 of damping rubber body of vulcanized tire:
adjusted by changing oil content
[0154] The test methods are the same as in the working Examples A
except for the following method.
<Steering Stability>
[0155] Each of the test tires was mounted on the above rim and
mounted on all wheels of the above test car under the condition of
the above inner pressure. While the test 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 28 being 100, wherein a larger numerical value is
better.
[0156] The test results are shown in Table 2.
TABLE-US-00002 TABLE 2 Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex. 32
Ex. 33 Figure showing FIG. 1 FIG. 1 FIG. 1 FIG. 1 FIG. 1 FIG. 1
FIG. 1 Cross section of Tire Presence (P) A P P p p P P or Absence
(A) of Damping rubber body Ratio (H1/H2) -- 0.4 0.5 0.7 1.0 1.2 0.7
of Hardness H1 of Damping rubber body and Hardness H2 of Tread
rubber Ratio (W1/W2) -- 100 100 100 100 100 50 of Width W1 of
Damping rubber body and Width W2 of Belt layer [%] Noise [index] 95
105 102 100 98 96 96 performance [larger is better] Tire mass
[index] 110 100 100 100 100 100 106 [larger is better] Steering
[index] 115 100 103 105 107 109 112 stability [larger is better]
Ex. 34 Ex. 35 Ex. 36 Ex. 37 Ex. 38 Ex. 39 Figure showing FIG. 1
FIG. 1 FIG. 1 FIG. 1 FIG. 2 FIG. 3 Cross section of Tire Presence
(P) P P P P P P or Absence (A) of Damping rubber body Ratio (H1/H2)
0.7 0.7 0.7 0.7 0.7 0.7 of Hardness H1 of Damping rubber body and
Hardness H2 of Tread rubber Ratio (W1/W2) 60 70 130 140 100 100 of
Width W1 of Damping rubber body and Width W2 of Belt layer [%]
Noise [index] 97 98 103 105 98 96 performance [larger is better]
Tire mass [index] 104 102 98 96 100 100 [larger is better] Steering
[index] 110 105 103 101 106 107 stability [larger is better]
[0157] From the test results, the tires as the Examples could
prevent the deterioration of the uniformity after puncture repair
while suppressing the running noise. Further, by setting the ratio
(H1/H2) of the hardness H1 of the damping rubber body and the
hardness H2 of the tread rubber to the preferable range, it was
possible that the steering stability was improved.
Working Examples C
[0158] Tires having the basic structure shown in FIG. 1 and the
noise damper described in the working Examples B, the damping
rubber body described in the working Examples A, and the tread
rubber of Table 3 were manufactured, and then their performance was
evaluated (Examples 40 to 46). The specifications common to each of
the Examples are the same as those of the working Examples A except
for those listed in Table 3 and shown below. Note that the common
specifications of the noise damper are as in the working Examples
B. The common specifications of the damping rubber body are as in
the working Examples A.
[0159] Composition of Tread rubber:
[0160] Same as in the working Examples A except for carbon black,
silica, and sulfur shown below
[0161] Carbon black (N220): A (arbitrary) phr
[0162] Silica (VN3, 1115MP): B (arbitrary) phr
[0163] Sulfur: C (arbitrary) phr
[0164] The test methods are the same as in the working Examples A
except for the following methods.
<Wet Grip Performance>
[0165] Each of the test tires was mounted on the above rim and
mounted on all wheels of the above test car under the condition of
the above inner pressure. While the test car was driven on a wet
asphalt road, grip performance was evaluated by the driver's
feeling. The evaluation was indicated by an index based on the
Example 40 being 100, wherein a larger numerical value is
better.
<Rolling Resistance Performance>
[0166] Each of the test tires was mounted on the above rim, and
then the rolling resistance under the condition of the above inner
pressure, tire load of 4.8 kN, and at a speed of 80 km/h was
measured by using a rolling resistance tester. The results are
indicated by an index based on the reciprocal of the value of the
Example 40 being 100, wherein a larger numerical value is
better.
<Anti-Wear Performance>
[0167] Each of the test tires was mounted on the above rim and
mounted on all wheels of the above test car under the condition of
the above inner pressure. Then the test car was driven on highways
and general roads (including city roads and mountain roads) with
two members on the car for a total of 340 km. Then a wear index
(running distance/wear amount) was measured in three block-like
portions on a tire circumference of a shoulder land region of the
tread portion, and then an average value thereof was calculated.
The results are indicated by an index based on the reciprocal of
the wear index of the Example 40 being 100, wherein a larger
numerical value is better.
[0168] The test results are shown in Table 3.
TABLE-US-00003 TABLE 3 Ex. 40 Ex. 41 Ex. 42 Ex. 43 Ex. 44 Ex. 45
Ex. 46 Loss tangent tan .delta. at zero 0.35 0.40 0.50 0.50 0.50
0.50 0.50 degrees Celsius of Tread rubber Loss tangent tan .delta.
at 70 0.25 0.25 0.25 0.20 0.10 0.10 0.10 degrees Celsius of Tread
rubber (1.4 .times. A1 + A2)/A3 15.0 15.0 15.0 15.0 15.0 20.0 37.5
Noise performance [index] 100 100 100 100 100 100 100 [larger is
better] wet grip performance [index] 100 105 110 110 110 110 110
[larger is better] Rolling resistance [index] 100 100 100 105 110
110 110 performance [larger is better] Anti-wear performance
[index] 100 100 100 100 100 105 115 [larger is better]
[0169] From the test results, the tires as the Examples could
prevent the deterioration of the uniformity while suppressing the
running noise. Further, by setting the loss tangents tan .delta.
(zero degrees Celsius, 70 degrees Celsius), the carbon black
content, the silica content, and the sulfur content to the
preferable ranges, it was possible that the wet grip performance,
the rolling resistance performance, and the anti-wear performance
were improved.
* * * * *