Resilient tires and wheels – Tires – resilient – Anti-skid devices
Utility Patent
1998-11-04
2001-01-02
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209100, C152S450000, C152S454000, C156S110100
Utility Patent
active
06167932
ABSTRACT:
The present invention relates to a pneumatic tire for passenger cars in which a novel harshness factor is specifically defined to reduce the so called harshness noise without deteriorating the steering stability.
BACKGROUND
When a passenger car runs on paved roads having joints, humps, hollows and the like, the shocks thereby are transmitted from the tires to the inside of the car through the suspension mechanisms and felt as sound as well as shocks. This sound is called ‘harshness noise’.
The harshness noise can be reduced by using a relatively soft tread rubber for example. In this case however, the steering stability decreases.
It is therefore an object of the present invention to provide a pneumatic tire for passenger cars in which the harshness noise is reduced without deteriorating the steering stability.
BRIEF SUMMARY OF THE INVENTION
According to the present invention a pneumatic tire for passenger cars comprises a tread portion, and
when the tire is mounted on a regular rim and inflated to 200 kPa and loaded with no tire load, the tread portion is provided with a profile comprising a crown part having a radius of curvature R
1
in (mm) and shoulder parts each having a radius of curvature R
2
in (mm), the crown part defined as extending from the tire equator to an axial position on each side thereof spaced at an axial distance of 35% of a tread width from the tire equator, the shoulder part defined as extending on one side of the tire equator from an axial position spaced at an axial distance of 37.5% of the tread width from the tire equator to an axial position spaced at an axial distance of 45% of the tread width from the tire equator, wherein
a harshness factor HF is set in the range of from 3.2 to 3.5,
the harshness factor HF defined as
HF=−
0.133×(R
1
/
100
)+0.245×(R
1
/R
2
)−0.183×(
Kv/
10)+3.898
wherein
Kv is the vertical spring constant (KN/mm) of the tire.
The ‘tread width TW’ is the maximum axial width of the ground contacting area under a standard condition in which the tire is mounted on a regular rim and inflated to a standard pressure of 200 KPa and then loaded with a normal load W
0
. The 'regular rim' is the rim officially approved for the tire by standard organization, i.e. JATMA (Japan and Asia), T&RA (North America), ETRTO (Europe), STRO (Scandinavia) and the like. The normal load W
0
is 75% of the maximum load specified by the same organization. Incidentally, the reason why 200 kPa is used is that this value is typical of almost all tire sizes as service pressure.
The inventors discovered that the harshness noise of passenger car tires can be reduced by optimizing the tread crown radius, tread shoulder radius and tire vertical spring constant, and that it is effective to limit the newly established harshness factor HF into a specific range. If the harshness factor HF is less than 3.2, the harshness noise can not decrease effectively. If the harshness factor HF is more than 3.5, the steering stability deteriorates.
An embodiment of the present invention will now be described in detail in conjunction with the accompanying drawings.
REFERENCES:
patent: 4-218404 (1992-08-01), None
Idei Mitsushige
Tagashira Kenji
Yamamoto Akio
Yamashita Fumikazu
Birch & Stewart Kolasch & Birch, LLP
Johnstone Adrienne C.
Sumitomo Rubber Industries Ltd.
LandOfFree
Pneumatic tire for passenger cars having specified harshness... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pneumatic tire for passenger cars having specified harshness..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic tire for passenger cars having specified harshness... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2536843