Resilient tires and wheels – Tires – resilient – Anti-skid devices
Patent
1996-04-18
1999-12-07
Maki, Steven D.
Resilient tires and wheels
Tires, resilient
Anti-skid devices
B60C 1103, B60C11300
Patent
active
059966602
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a pneumatic tire capable of reducing discomfort due to noises on traveling by establishing an alignment (sequence) of pattern composing units in a tire tread according to a sequence of numbers obtained by a chaotic function.
BACKGROUND OF THE INVENTION
Various tread patterns are employed in a tire tread according to conditions of a vehicle and road surface. For a tread pattern, block, rib, lug and other patterns comprising units of a certain pattern, that is, pattern composing units repetitively provided in the circumferential direction of tire, are often used by circumferentially forming grooves in the direction of tire's axis with a spacing between them, or providing rib grooves circumferentially staggered.
In a tire with such patterns repetitively provided, a noise is repetitively produced between the tire and a road surface, because the pattern composing units in an alignment (sequence) come in contact with the road surface sequentially as the tire travels. The noise produced by the pattern composing units (hereinafter referred to as pitch noise) is generally uncomfortable, and improvement of the noise is desired.
In order to improve the noise, the so-called pitch variation method has been conventionally employed for dispersing the noise in a wide frequency band, and changing it to a white noise by arranging pattern composing units different in pitch or length in the circumferential direction of tire.
For changing it to a white noise, a lot of suggestions have been made, and provision of pitches of a periodic sequence in a manner of sinusoidal function is suggested, for example, in Japanese Patent Publication Nos. 58-2844 (Japanese Laid-open Patent Nos. 55-8904) and 3-23366 (54-115801). It is also suggested to provide a random sequence of pitches of pattern composing units as described in Japanese Patent Publication No. 62-41122 (57-114706).
It is suggested to provide s sequence of two pitches of two pattern composing units (the number s=2) as described in Japanese Patent Publication Nos. 51-41723 (Japanese Laid-open Patent No. 50-20402) and Japanese Laid-open Patent No. 4-363234.
SUMMARY OF THE INVENTION
The former suggestion of providing pitches of a periodic sequence in a manner of sinusoidal function still provides such advantage that a variation of rigidity between adjacent pattern composing units is low, and abnormal wear is reduced, because the pitches are continuously and periodically changed. However, the variation of rigidity between the pattern composing units is periodically changed in correspondence with change in pitch. Therefore, a force variation (RFV) in the radial direction of a specific degree component that is consistent with a periodicity is increased, an abnormal vibration is produced, and the uncomfortable noise may be increased.
In the case of providing a random sequence of pitches of pattern composing units, no periodic regularity is obtained, contrarily to the periodic sequence. Thus, the specific degree component of force variation is never increased, and an abnormal vibration and noise are rarely produced. However, since a difference between pitches of adjacent pattern composing units are relatively high, it is a problem that an abnormal wear is often caused.
It is also proved that the number s of types of pitch length of the pattern composing units should be preferably three or more, because an effect of pitch variation is insufficient, and the noise cannot be sufficiently changed to a white noise, if it is two.
On the other hand, it is relatively easy for manufacturers to increase the number s of types itself owing to recent advance in manufacture of molds. However, it is not clearly proved that the noise can be reduced by increasing the number s of types, and a new method is demanded.
For reducing the noise of tire, on the basis of providing pattern composing units, the inventors found through various developments that: are
As a result of studies and developments conducted for determining an alignment of pattern comp
REFERENCES:
patent: 1956011 (1934-04-01), Evans
patent: 2124821 (1938-07-01), Hubach
patent: 2878852 (1959-03-01), Lippmann et al.
patent: 4178199 (1979-12-01), Lippman et al.
patent: 4442499 (1984-04-01), Sekula et al.
patent: 4474223 (1984-10-01), Landers
patent: 5371685 (1994-12-01), Bandel et al.
Title for Japan 54-115801.
Aoki Chieko
Kakumu Kiichiro
Maki Steven D.
Sumitomo Rubber Industries Ltd.
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